"We got a response from *ip* that we didn't ask for, ignoring"

[Tartafive]

Trying doing a co-op and i got this error while joining my mate's game. what can i do for fix it?

[Tartafive]

I want to specify that this happend on BO2

[Dss0]

Tartafive so this is zombies i assume?
Can't really tell you what that message is caused by exactly but:

• the host has to start the game before anyone can connect
• the host can try setting zombies_minplayers to 2
• the host can try forwarding port 4976 udp in their router
• difficulty has to be easy

[Tartafive]

Dss0 Forwarded the port but still nothing.