Steam – Synergy (Half-Life 2 co-op mod) can’t connect through SteamID number like Sven (HL1 co-op mod)

In Sven Co-op you can connect to your friends' servers by typing:

connect STEAM_0:1:12345678

I'm changing the numbers of these values in the post, except for the headings.

To go through Steam's network and bypass the ports that may be blocking you. This is useful since I don't have the ability to open any ports on my network.
The connection ID is gained by typing 'status' into the console.

The problem is for Synergy, connecting by this ID results in a bad address error. The address given when typing 'status' into console for Sven has a different heading as well.

steamid : [A:1:12345678:12345] (90128200123453894)

Have tried:

connect STEAM_[A:1:170001222:12222] (90128200959653894)
connect STEAM_A:1:170000222:12222
connect STEAM_175000022:122227
connect STEAM_A:1:170000222
connect STEAM_175200002
connect STEAM_A:1:175000022

All of which did not work.

In Sven, status returns only what is shown in the first bracket, but also has the heading 0:1: instead of A:1.

Best Answer

Sven Co-op has implemented connecting through SteamID in its 2019-04-01 v5.19 [Build 3695902] update:

Implemented Steam P2P (peer-to-peer) based network layer. Allows players to host listen servers without the hassle of port forwarding. (Usage: "connect STEAM_1:1:12345678")

I can't find any source that says the same has been implemented for Synergy. I believe it won't work because the functionality is not supported by Synergy.