diff --git a/packages/playwright-core/src/client/network.ts b/packages/playwright-core/src/client/network.ts
index f2314f1328..4e9ea285ce 100644
--- a/packages/playwright-core/src/client/network.ts
+++ b/packages/playwright-core/src/client/network.ts
@@ -346,9 +346,7 @@ export class Route extends ChannelOwner<channels.RouteChannel> implements api.Ro
 
   async fulfill(options: { response?: api.APIResponse, status?: number, headers?: Headers, contentType?: string, body?: string | Buffer, json?: any, path?: string } = {}) {
     await this._handleRoute(async () => {
-      await this._wrapApiCall(async () => {
-        await this._innerFulfill(options);
-      }, { internal: true });
+      await this._innerFulfill(options);
     });
   }
 
diff --git a/packages/playwright-core/src/server/dispatchers/dispatcher.ts b/packages/playwright-core/src/server/dispatchers/dispatcher.ts
index b73c07bae1..ca1db256e9 100644
--- a/packages/playwright-core/src/server/dispatchers/dispatcher.ts
+++ b/packages/playwright-core/src/server/dispatchers/dispatcher.ts
@@ -24,6 +24,7 @@ import { TargetClosedError, isTargetClosedError, serializeError } from '../error
 import { SdkObject } from '../instrumentation';
 import { isProtocolError } from '../protocolError';
 import { compressCallLog } from '../callLog';
+import { methodMetainfo } from '../../utils/isomorphic/protocolMetainfo';
 
 import type { CallMetadata } from '../instrumentation';
 import type { PlaywrightDispatcher } from './playwrightDispatcher';
@@ -304,6 +305,12 @@ export class DispatcherConnection {
       return;
     }
 
+    if (methodMetainfo.get(dispatcher._type + '.' + method)?.internal) {
+      // For non-js ports, it is easier to detect internal calls here rather
+      // than generate protocol metainfo for each language.
+      validMetadata.internal = true;
+    }
+
     const sdkObject = dispatcher._object instanceof SdkObject ? dispatcher._object : undefined;
     const callMetadata: CallMetadata = {
       id: `call@${id}`,
diff --git a/utils/generate_dotnet_channels.js b/utils/generate_dotnet_channels.js
index b6f0b7716e..15a04af5f1 100644
--- a/utils/generate_dotnet_channels.js
+++ b/utils/generate_dotnet_channels.js
@@ -136,7 +136,7 @@ function properties(properties, indent, onlyOptional, parentName, level) {
       if (name === 'android' || name === 'electron')
         continue;
       if (name.startsWith('$mixin')) {
-        visitProperties(mixins.get(value).properties, parentName + toTitleCase(name));
+        visitProperties(mixins.get(value).properties, parentName);
         continue;
       }
       const inner = inlineType(value, indent, parentName + toTitleCase(name), level + 1);