Local offline LAN server, joining stuck on "authenticating with STEAM..."

Hey. I’m trying to play with another person on a LAN. Neither the router nor the computers are connected to the Internet, and steam is in offline mode. Yet with either computer hosting, I still get “authenticating with STEAM…” I’ve also tried adding “-insecure” to the launch options, as that solved a similar problem we had with Left 4 Dead 2, but that changed nothing.

make sure either sv_lan is set to 1 or that you are trying to join from different steam accounts.

Both of these are true. I’ve also tried connecting directly via IP instead of the server browser, but I didn’t think that would make a difference, and it didn’t.

http://i.imgur.com/RFbAhdE.jpg

So I tried it - started a 2player server through main menu with LAN checkbox ticked, and then joined by my internal IP address. ( connect 192.168… )

I had to use -multirun as I don’t have 2 PCs and 2 accounts to test this with. I was disconnected from the Internet and Steam was running in offine mode.

Try entering p2p_enabled 0 into your console before starting a server.

No go, Robro. I set it to 0 on both PCs and they tried connecting in either direction. Still stuck on Authenticating with Steam…

[editline]9th August 2016[/editline]

Just for completeness’ sake, I also disabled all addons and restarted Gmod on both machines. Still doesn’t want to connect.

I hate to be a bother with a bump, but is there any way I can bypass “authenticating with Steam”?

Just for more completeness I tried using -multirun to run two copies of GMod inside my own machine. The problem persists. I also tried tethering the phone to my PC and running Gmod in online mode but then I get a “LAN servers are restricted to local clients (class C)” error instead, even with both PCs put online via tethering.