Why doesn't connecting/disconnecting to the bot's Discord voice channel work?

Question

Python

I wanted to make a bot, the usual commands in text chats work, but connecting and disconnecting to voice channels does not work, I did not find any sensible guides.
This is what I was able to scoop out from existing guides:

@client.command(pass_context=True)
async def join(ctx):
  channel= ctx.message.author.voice.channel
  await channel.connect()
  
@client.command(pass_context=True)
async def leave(ctx):
  server=ctx.message.server
  voice_client=client.voice_client_in(server)
  await voice_client.disconnect()