Cannot host steam sessions in 4.26, 4.27 or 5.0.

I have been working 3 days straight at trying to figure out why I cannot host Steam sessions for others to find online.

The problem:
My friends can all host sessions successfully, I can find them and join them (usually)
I can host a session. However, they cannot find my session and therefor cannot join me.
Sometimes, I cannot see their sessions, it seems very intermittent sometimes.

What I have done:
I have tried from the editor with standalone game, launched game from fire explorer, packaged game as development while including the steamapp id txt, as well as shipping.
Followed unreal’s documentation for setting up steam for the project(s), including the .ini file.
Installed the latest steamworks sdk(1.53)
Enabled OnlineSubsystemSteam
Proper execution of host, find, join session nodes.
I have tried unreals standard session classes.
I have tried SteamCore on the unreal marketplace, fancy plugin but no worky.
I have tried AdvancedSteamSessions plugin.
I have DMZ enabled for my PC via Router.
I have ports 7777, 2700-27100 port forwarded
I have query port set to 27015 and game port to 7777 in the .ini file
I have peer to peer connections enabled
I have firewall turned completely off on my pc, and have added exclusivity rules in the advanced settings allowing all traffic on all ports.
I have called my ISP to confirm that they are not filtering ports on their end.
I have connected directly to my modem to bypass all possible router interference.

^^^ Everything I have done I have also tried without. ^^^

I am getting VERY frustrated. I have googled solutions for hours upon hours, asked in help discords, asked the help of many of my friends and to no avail.

I’m pulling my hair out with this, I simply cannot decipher this issue! Please! Anyone with knowledge of networking, help me. Is this an issue I can fix without diving into C++? Can I even fix it with C++? Does anyone here have a working Steam Multiplayer game on 4.26 or higher?

Seeing your post sitting here 7 days no reply… I feel you man, it took me almost 3 weeks to work through this with dedicated server and listen server, and 3 months total, just to get my networking framework to work, using PacketHandlerComponents, etc. Here’s what I found:

  1. Using the Steam ‘Find Servers’ is almost useless, except if you’re using app_id 480, which is just for fun.
  2. I don’t recommend using ‘Stand Alone’ for testing. Notwithstanding all the videos that show this working, I have NEVER gotten it to work. I’m using 4.24.2 - I’m not sure why.
  3. Make your own server browser. It is not difficult and you can send your own session data so that you can find, sort, connect etc.
  4. You need to have a client and server on separate networks. I rent a server from Kamatera for my dedicated testing. But to debug my dedicated server, I need another machine on a different network (is use my phone hotspot and a laptop)
  5. Not delving into C++: this will be very problematical I think, except for the most basic of tutorial level. So I’d suggest you remove this constraint from your list.

To quickly note my experience with Steam networking: I have not ever work with such a difficult networking framework in my professional career, which included more than a year of remote print driver virtualization. There is little documentation that provides any utility for someone trying to figure this out and the doc that does exist is mostly the self-evident doc:

*** example of doc entry **
bool SomeFunctionToCall(param0, param1, param2, param3, param4, param5, param6, param7, param8, param9, param10)

SomeFunctionToCall() is a function to call;

Returns: returns true or false

** end doc entry

I have found most of my answers through

  1. Metric tons of trial & error (approximately 300+ hours of building/uploading/updating
  2. 15th comments down in some Stackexchange replys
  3. Prior knowledge of network/socket programming from 25 years professional software engineering experience and applying the theory to Steams networking (which acutally does a pretty good job of matching, so you CAN use other information to help
  4. Read and understand as much the C++ networking code as you can, even if you don’t use the C++, it will tell you what you need to know.

I am a single engineer on a game to be released in May 2022 and have nightmares about all the trouble ticket that will be coming in when release, just for the Steam networking. by the time of release I will have developed for 2 years, 3 months and I’d estimate about 4 months on networking alone.

I think other development TEAMS using UE4 have dedicated Steam network experts working on it full-time. I don’t have those resources. Probably you don’t either.

KEEP AT IT, NEVER GIVE UP: you will eventually work it out, as I have. Just factor in 5x more time to do something than you think it will actually take. It helps.

EDIT: I forgot to mention that any question I have ever asked about Steam networking has not been answered anywhere, except for 1, that referred me to a doc link like the above example.