Legend: Friend A, Friend B, Friend C

We all play For Honor on PS4



A couple days ago me and Friend A couldn't join each other due to our NAT types. I am playing on a open NAT type and he is playing on a "unknown" NAT type. Assuming Friend A's connection is the problem he tried all the steps to getting an open NAT type, in the end he still had an "unknown" NAT type and we still couldn't join each other. Two days after, Friend B hops online ( he has an open NAT type). Friend B invites me to a party and I successfully join. Then Friend B invites Friend A ( the one with the unknown NAT type) and he successfully joins as well. This confused me and Friend A because we both had thought that Friend A couldn't join anybody due to his NAT type. After this, we call Friend C to hop online to help test this issue. Friend C also has an open NAT type. He invites me (open NAT type) I successfully join. Next, he invites Friend B (open NAT type) he successfully join. Then he invites Friend A (unknown NAT type) he too successfully joins. Keep in mind that we all queued up and we all played Dominion without a problem. The problem at hand here is that Friend A cannot join my party and I cant join his. But, Friend A can join Friend B and C's party but neither Friend B and C can join Friend A's party invites. This is a very confusing matter and I wish for help ASAP.

This frustrates me because Friend A and I play For Honor the most and we can't seem to join each others party in the menu. PLEASE HELP.