diff --git a/app/forms/network-interface-create.tsx b/app/forms/network-interface-create.tsx
index 29758362a1..b1dc84aa42 100644
--- a/app/forms/network-interface-create.tsx
+++ b/app/forms/network-interface-create.tsx
@@ -16,7 +16,7 @@ import { SubnetListbox } from 'app/components/form/fields/SubnetListbox'
 import type { CreateSideModalFormProps } from 'app/forms'
 import { useParams } from 'app/hooks'
 
-const values = {
+const values: NetworkInterfaceCreate = {
   name: '',
   description: '',
   ip: '',
@@ -31,6 +31,7 @@ export default function CreateNetworkInterfaceSideModalForm({
   onSubmit,
   onSuccess,
   onError,
+  onDismiss,
   ...props
 }: CreateSideModalFormProps<NetworkInterfaceCreate, NetworkInterface>) {
   const queryClient = useApiQueryClient()
@@ -45,6 +46,7 @@ export default function CreateNetworkInterfaceSideModalForm({
         ...others,
       })
       onSuccess?.(data)
+      onDismiss()
     },
     onError,
   })
@@ -56,6 +58,7 @@ export default function CreateNetworkInterfaceSideModalForm({
       id={id}
       title={title}
       initialValues={initialValues}
+      onDismiss={onDismiss}
       onSubmit={
         onSubmit ||
         ((body) => {
diff --git a/app/forms/network-interface-edit.tsx b/app/forms/network-interface-edit.tsx
new file mode 100644
index 0000000000..9c13b0c686
--- /dev/null
+++ b/app/forms/network-interface-edit.tsx
@@ -0,0 +1,74 @@
+import invariant from 'tiny-invariant'
+
+import type { NetworkInterface, NetworkInterfaceUpdate } from '@oxide/api'
+import { useApiMutation, useApiQueryClient } from '@oxide/api'
+
+import { DescriptionField, Form, NameField, SideModalForm } from 'app/components/form'
+import type { EditSideModalFormProps } from 'app/forms'
+import { useParams } from 'app/hooks'
+
+export default function EditNetworkInterfaceSideModalForm({
+  id = 'edit-network-interface-form',
+  title = 'Edit network interface',
+  onSubmit,
+  onSuccess,
+  onError,
+  onDismiss,
+  initialValues,
+  ...props
+}: EditSideModalFormProps<NetworkInterfaceUpdate, NetworkInterface>) {
+  const queryClient = useApiQueryClient()
+  const pathParams = useParams('orgName', 'projectName')
+
+  const editNetworkInterface = useApiMutation('instanceNetworkInterfacesPutInterface', {
+    onSuccess(data) {
+      const { instanceName, ...others } = pathParams
+      invariant(instanceName, 'instanceName is required when posting a network interface')
+      queryClient.invalidateQueries('instanceNetworkInterfacesGet', {
+        instanceName,
+        ...others,
+      })
+      onSuccess?.(data)
+      onDismiss()
+    },
+    onError,
+  })
+
+  return (
+    <SideModalForm
+      id={id}
+      title={title}
+      initialValues={initialValues}
+      onDismiss={onDismiss}
+      onSubmit={
+        onSubmit ||
+        ((body) => {
+          const { instanceName, ...others } = pathParams
+          const interfaceName = initialValues.name
+          invariant(
+            interfaceName,
+            'interfaceName is required when updating a network interface'
+          )
+          invariant(
+            instanceName,
+            'instanceName is required when posting a network interface'
+          )
+
+          editNetworkInterface.mutate({
+            instanceName,
+            interfaceName,
+            ...others,
+            body,
+          })
+        })
+      }
+      submitDisabled={editNetworkInterface.isLoading}
+      error={editNetworkInterface.error?.error as Error | undefined}
+      {...props}
+    >
+      <NameField id="nic-name" />
+      <DescriptionField id="nic-description" />
+      <Form.Submit>Save changes</Form.Submit>
+    </SideModalForm>
+  )
+}
diff --git a/app/pages/__tests__/click-everything.e2e.ts b/app/pages/__tests__/click-everything.e2e.ts
index becc865618..eea7f46508 100644
--- a/app/pages/__tests__/click-everything.e2e.ts
+++ b/app/pages/__tests__/click-everything.e2e.ts
@@ -1,6 +1,6 @@
 import { test } from '@playwright/test'
 
-import { expectNotVisible, expectVisible } from 'app/util/e2e'
+import { expectNotVisible, expectRowVisible, expectVisible } from 'app/util/e2e'
 
 test("Click through everything and make it's all there", async ({ page }) => {
   await page.goto('/')
@@ -107,7 +107,13 @@ test("Click through everything and make it's all there", async ({ page }) => {
 
   // Instance networking tab
   await page.click('role=tab[name="Networking"]')
-  await expectVisible(page, ['role=cell[name="my-nic"]'])
+  await expectRowVisible(page, 'my-nic', [
+    '',
+    'my-nic',
+    'a network interface',
+    '172.30.0.10',
+    'primary',
+  ])
   await page.click('role=button[name="Add network interface"]')
 
   // Add network interface
@@ -129,15 +135,41 @@ test("Click through everything and make it's all there", async ({ page }) => {
   await page.click('role=button[name="Add network interface"]')
   await expectVisible(page, ['role=cell[name="nic-2"]'])
 
-  // Delete just-added network interface
+  // Make this interface primary
+  await page
+    .locator('role=row', { hasText: 'nic-2' })
+    .locator('role=button[name="Row actions"]')
+    .click()
+  await page.click('role=menuitem[name="Make primary"]')
+  await expectRowVisible(page, 'my-nic', [
+    '',
+    'my-nic',
+    'a network interface',
+    '172.30.0.10',
+    '',
+  ])
+  await expectRowVisible(page, 'nic-2', ['', 'nic-2', null, null, 'primary'])
+
+  // Make an edit to the network interface
   await page
     .locator('role=row', { hasText: 'nic-2' })
     .locator('role=button[name="Row actions"]')
     .click()
+  await page.click('role=menuitem[name="Edit"]')
+  await page.fill('role=textbox[name="Name"]', 'nic-3')
+  await page.click('role=button[name="Save changes"]')
+  await expectNotVisible(page, ['role=cell[name="nic-2"]'])
+  await expectVisible(page, ['role=cell[name="nic-3"]'])
+
+  // Delete just-added network interface
+  await page
+    .locator('role=row', { hasText: 'nic-3' })
+    .locator('role=button[name="Row actions"]')
+    .click()
   await page.click('role=menuitem[name="Delete"]')
   // Close toast, it holds up the test for some reason
   await page.click('role=button[name="Dismiss notification"]')
-  await expectNotVisible(page, ['role=cell[name="nic-2"]'])
+  await expectNotVisible(page, ['role=cell[name="nic-3"]'])
 
   // Snapshots page
   await page.click('role=link[name*="Snapshots"]')
diff --git a/app/pages/project/instances/instance/tabs/NetworkingTab.tsx b/app/pages/project/instances/instance/tabs/NetworkingTab.tsx
index d756c192d6..5f49251ab9 100644
--- a/app/pages/project/instances/instance/tabs/NetworkingTab.tsx
+++ b/app/pages/project/instances/instance/tabs/NetworkingTab.tsx
@@ -1,19 +1,21 @@
 import { useState } from 'react'
 
-import type { NetworkInterface } from '@oxide/api'
+import type { NetworkInterface, NetworkInterfaceUpdate } from '@oxide/api'
 import { useApiMutation, useApiQuery, useApiQueryClient } from '@oxide/api'
 import type { MenuAction } from '@oxide/table'
 import { useQueryTable } from '@oxide/table'
 import {
+  Badge,
   Button,
   Delete16Icon,
   EmptyMessage,
-  Info16Icon,
   Networking24Icon,
-  Tooltip,
+  OpenLink12Icon,
+  Success12Icon,
 } from '@oxide/ui'
 
 import CreateNetworkInterfaceSideModalForm from 'app/forms/network-interface-create'
+import EditNetworkInterfaceSideModalForm from 'app/forms/network-interface-edit'
 import { useParams, useToast } from 'app/hooks'
 
 export function NetworkingTab() {
@@ -22,6 +24,7 @@ export function NetworkingTab() {
   const addToast = useToast()
 
   const [createModalOpen, setCreateModalOpen] = useState(false)
+  const [editing, setEditing] = useState<NetworkInterfaceUpdate | null>(null)
 
   const getQuery = ['instanceNetworkInterfacesGet', instanceParams] as const
 
@@ -36,12 +39,42 @@ export function NetworkingTab() {
     },
   })
 
+  const editNic = useApiMutation('instanceNetworkInterfacesPutInterface', {
+    onSuccess() {
+      queryClient.invalidateQueries(...getQuery)
+    },
+  })
+
+  const instanceStopped =
+    useApiQuery('projectInstancesGetInstance', instanceParams).data?.runState === 'stopped'
+
   const makeActions = (nic: NetworkInterface): MenuAction[] => [
+    {
+      label: 'Make primary',
+      onActivate() {
+        editNic.mutate({
+          ...instanceParams,
+          interfaceName: nic.name,
+          body: { ...nic, makePrimary: true },
+        })
+      },
+      disabled: nic.primary || !instanceStopped,
+    },
+    {
+      label: 'Edit',
+      onActivate() {
+        // TODO: Revisit after https://github.com/oxidecomputer/omicron/pull/1288 is merged
+        setEditing({ ...nic, makePrimary: nic.primary })
+      },
+      disabled: !instanceStopped,
+    },
     {
       label: 'Delete',
+      className: 'destructive',
       onActivate: () => {
         deleteNic.mutate({ ...instanceParams, interfaceName: nic.name })
       },
+      disabled: !instanceStopped,
     },
   ]
 
@@ -55,48 +88,60 @@ export function NetworkingTab() {
     />
   )
 
-  const instanceStopped =
-    useApiQuery('projectInstancesGetInstance', instanceParams).data?.runState === 'stopped'
-
   const { Table, Column } = useQueryTable(...getQuery)
   return (
     <>
-      <div className="mb-3 flex items-center justify-end space-x-4">
-        {
-          // TODO: update icon color
-          // TODO: the tooltip pops up on the right edge of the icon instead of
-          // the middle, wtf. not worth fixing because we're going to redo
-          // Tooltip anyway
-          // TODO: would be cool to also show the tooltip on button hover when it's disabled
-          !instanceStopped && (
-            <Tooltip
-              id="add-nic-tooltip"
-              content="A network interface cannot be added unless the instance is stopped."
-            >
-              <Info16Icon className="cursor-default text-secondary" />
-            </Tooltip>
-          )
-        }
-        <Button
-          size="xs"
-          variant="default"
-          onClick={() => setCreateModalOpen(true)}
-          disabled={!instanceStopped}
-        >
-          Add network interface
-        </Button>
-        <CreateNetworkInterfaceSideModalForm
-          isOpen={createModalOpen}
-          onDismiss={() => setCreateModalOpen(false)}
-          onSuccess={() => setCreateModalOpen(false)}
-        />
-      </div>
+      <h2 id="network-interfaces" className="mb-4 text-mono-sm text-secondary">
+        Network Interfaces
+      </h2>
       <Table makeActions={makeActions} emptyState={emptyState}>
         <Column accessor="name" />
         <Column accessor="description" />
         {/* TODO: mark v4 or v6 explicitly? */}
         <Column accessor="ip" />
+        <Column
+          accessor="primary"
+          cell={({ value }) =>
+            value && (
+              <>
+                <Success12Icon className="text-accent mr-1" />
+                <Badge variant="secondary">primary</Badge>
+              </>
+            )
+          }
+        />
       </Table>
+      <div className="mt-4 flex flex-col gap-3">
+        <div className="flex gap-3">
+          <Button
+            size="xs"
+            variant="default"
+            onClick={() => setCreateModalOpen(true)}
+            disabled={!instanceStopped}
+          >
+            Add network interface
+          </Button>
+        </div>
+        {!instanceStopped && (
+          <span className="max-w-xs text-sans-sm text-secondary">
+            A network interface cannot be created or edited without{' '}
+            <a href="#/" className="text-accent-secondary">
+              stopping the instance
+              <OpenLink12Icon className="ml-1 pt-[1px]" />
+            </a>
+          </span>
+        )}
+      </div>
+
+      <CreateNetworkInterfaceSideModalForm
+        isOpen={createModalOpen}
+        onDismiss={() => setCreateModalOpen(false)}
+      />
+      <EditNetworkInterfaceSideModalForm
+        isOpen={!!editing}
+        initialValues={editing || {}}
+        onDismiss={() => setEditing(null)}
+      />
     </>
   )
 }
diff --git a/app/pages/project/networking/VpcPage/tabs/VpcRoutersTab.tsx b/app/pages/project/networking/VpcPage/tabs/VpcRoutersTab.tsx
index 3503979bdf..cc87019b65 100644
--- a/app/pages/project/networking/VpcPage/tabs/VpcRoutersTab.tsx
+++ b/app/pages/project/networking/VpcPage/tabs/VpcRoutersTab.tsx
@@ -41,13 +41,11 @@ export const VpcRoutersTab = () => {
         </Button>
         <CreateVpcRouterForm
           isOpen={createModalOpen}
-          onSuccess={() => setCreateModalOpen(false)}
           onDismiss={() => setCreateModalOpen(false)}
         />
         <EditVpcRouterForm
           isOpen={!!editing}
           initialValues={editing || {}}
-          onSuccess={() => setEditing(null)}
           onDismiss={() => setEditing(null)}
         />
       </div>
diff --git a/app/util/e2e.ts b/app/util/e2e.ts
index a01721d08c..c411fe6361 100644
--- a/app/util/e2e.ts
+++ b/app/util/e2e.ts
@@ -32,11 +32,15 @@ export async function expectNotVisible(page: Page, selectors: string[]) {
 export async function expectRowVisible(
   page: Page,
   rowSelectorText: string,
-  cellTexts: string[]
+  cellTexts: Array<string | null>
 ) {
   const row = page.locator(`tr:has-text("${rowSelectorText}")`)
   await expect(row).toBeVisible()
   for (let i = 0; i < cellTexts.length; i++) {
-    await expect(row.locator(`role=cell >> nth=${i}`)).toHaveText(cellTexts[i])
+    const text = cellTexts[i]
+    if (text === null) {
+      continue
+    }
+    await expect(row.locator(`role=cell >> nth=${i}`)).toHaveText(text)
   }
 }
diff --git a/libs/api-mocks/msw/handlers.ts b/libs/api-mocks/msw/handlers.ts
index 978769d113..f4f60842a1 100644
--- a/libs/api-mocks/msw/handlers.ts
+++ b/libs/api-mocks/msw/handlers.ts
@@ -528,6 +528,40 @@ export const handlers = [
     }
   ),
 
+  rest.put<
+    Json<Api.NetworkInterfaceUpdate>,
+    NetworkInterfaceParams,
+    Json<Api.NetworkInterface> | PostErr
+  >(
+    '/api/organizations/:orgName/projects/:projectName/instances/:instanceName/network-interfaces/:interfaceName',
+    (req, res, ctx) => {
+      const [nic, err] = lookupNetworkInterface(req.params)
+      if (err) return res(err)
+
+      if (req.body.name) {
+        nic.name = req.body.name
+      }
+      if (typeof req.body.description === 'string') {
+        nic.description = req.body.description
+      }
+      if (
+        typeof req.body.make_primary === 'boolean' &&
+        req.body.make_primary !== nic.primary
+      ) {
+        if (nic.primary) {
+          return res(badRequest('Cannot remove the primary interface'))
+        }
+        db.networkInterfaces
+          .filter((n) => n.instance_id === nic.instance_id)
+          .forEach((n) => {
+            n.primary = false
+          })
+        nic.primary = !!req.body.make_primary
+      }
+      return res(ctx.status(204))
+    }
+  ),
+
   rest.delete<never, NetworkInterfaceParams, GetErr>(
     '/api/organizations/:orgName/projects/:projectName/instances/:instanceName/network-interfaces/:interfaceName',
     (req, res, ctx) => {