Can Not Join 1 Specific Friend *Resolved?*

[grimrebuke]

One friend and I are unable to join each other's sessions. It bails at the data transfer message then says unable to connect.

1. We are both on PC. We have tried enabling and disabling cross-play
2. We are able to connect to other people's sessions, we are able to both connect to a third session. We simply can not connect to each other's.
3. We've tried un-friending and friending each other again.
4. We've both set allowed connections to "public".

We think we've nailed down the issue and the solution (special thanks to the Tabeltop Simulator community):

TLDR - go to the Steam client, select "Steam" >> Settings >> In Game
Scroll to bottom and set Steam Networking to "Never"

Long explanation - Steam typically handles Peer to Peer networking on their network by acting as a kind of proxy. IE - I connect to Steam, you connect to Steam, and Steam routes traffic between us. This works fine even behind firewalls and NAT'ing because each of us connected to Steam outbound.
To improve latency, Steam supports direct connections. When you and I go to play a game together, Steam send you my IP address and sends me yours and our two machines try to talk to each other. Here's the rub: a lot of us are behind firewalls that will allow the outbound connection, but not an incoming connection. And if you're doing any kind of NAT'ing, the router with the public IP address won't know who to send the incoming connections to.
The default option for this behavior appears to have the clients ping each other to see if the latency between you and me is lower than it would be if we routed through Steam's network. If it is lower, then it tells us to go talk to each other. In our case, we could ping the other's public IP so it switched to the direct P2P, but then the data connection wouldn't happen and the connection would time out.

Setting the option to "never" will prevent sharing your IP address with the other client/game and force Steam to act as the "middle-man".

This is what we've been able to suss out and so far our testing is allowing us to connect using the "never" setting in the Steam client. If you try this, please post your results. For Democracy!

[HeadCheater]

Same here..

[Erkel Wolf]

same for me. able to join and be join by random people but the friend i wish to play with no.
we cant join each other.

[Karn (BallnButAtWhatCost)]

Same here, still ongoing.

[yung_brekky]

Can play with anybody else except my friend who just bought the game. It's so wild it's as if we've been assigned the same network ID for some reason, we literally cannot exist in the gameworld together at the same time.
Please Arrowhead, SOS

[JJ [Phantom][RSIC]]

Same.
And today I encountered a new bug. Now I am crashing when the game is open for 2 minutes.
Completely new.

[Jyria]

Returning players here, all of us cannot connect to eachother

[Speed Stake]

Same, he joined an in progress mission and it immediately booted me to my ship. Tried some back and forth fixes and we were able to confirm its something between only our accounts that refuse to sync.

[Unluck]

This has been happening sporadically for weeks now. You can try to set your steam download region to somewhere else and have your friends set theirs to the same place. That worked for us for a while but then like tonight the problem is back again. I literally live 5 mins from my friends house.

[Joey5729]

Bumping

[King]

wow joey5729 crazy seeing you here. almost like we are having the same issue lol.

[DieHard]

Originally posted by HeadCheater:

Same here..

Likewise. Two or three days now. Two of my friends can't link up. We're all PC. Other friends can join me, and I can also go into the match making for p2p

[wil4me]

Yup. Multiplayer used to work here, then suddenly stopped working completely. Unable to join anyone or be joined by anyone.

[Graph0115]

THIS WORKED MY GOD YOU ARE A GENIUS, STEAM NETWORKING TO NEVER ACTUALLY WORKED MY GOD THAT WAS CRAZY MAN