GraphQL Subscription problem

network-change.object-type.ts

import { ObjectType, Field } from '@nestjs/graphql';
import { Link } from './link.object-type';
import { Node } from './node.object-type';

@ObjectType()
export class NetworkChange {
  @Field(() => String, { defaultValue: '', nullable: true })
  test: string;
}

network.resolver.ts

import {
  Resolver,
  Query,
  Args,
  Mutation,
  ID,
  Subscription,
} from '@nestjs/graphql';
import { Link } from './object-types/link.object-type';
import { CreateLinkInput } from './dto/create-link.input';
import { CaseService } from '../workspace/services/case.service';
import { Inject } from '@nestjs/common';
import { PUB_SUB } from '@infrastructure/providers/pub-sub.provider';
import { NetworkChange } from './object-types/network-change.object-type';
import { RedisPubSub } from 'graphql-redis-subscriptions';
const LINK_ADDED = 'linkAdded';

@Resolver(() => Network)
export class NetworkResolver {
  constructor(
    @Inject(PUB_SUB) private readonly pubSub: RedisPubSub,
  ) {}

  @Mutation(() => Link)
  createLink(@Args('createLinkInput') createLinkInput: CreateLinkInput) {
    this.pubSub.publish('networkChanged', {
      test: '',
    });
    return this.networkService.createLink(createLinkInput);
  }

  @Subscription(() => NetworkChange, {
    resolve: (p) => {
      return p
    }
  })
  networkChanged() {
    return this.pubSub.asyncIterator('networkChanged');
  }
}

pub-sub.provider.ts

import { RedisPubSub } from 'graphql-redis-subscriptions';
import Redis from 'ioredis';
export const PUB_SUB = 'PUB_SUB';

export const pubSubProvider = {
  provide: PUB_SUB,
  useFactory: () => {
    const options = {
      host: 'localhost',
      port: 6379,
      retryStrategy: (times) => Math.min(times * 50, 2000),
    };

    return new RedisPubSub({
      publisher: new Redis(options),
      subscriber: new Redis(options),
    });
  },
};