There really should be.
So I will ask it here.
Is there some kind of service like unity has in the new UNET when you can sign your project to make a matchmaker for your game?
After signing your project in their website, you can simply create a game with a certain name and then find where ever your are.
For Multiplayer programming you mean? Typically they just end up in the Blueprint or C++ forum, it would be a bit of a pain having a networking subforum that has mixed languages inside it. A lot of Network folks like to go the C++ route 
I see, Thanks.
Any idea about my other question?
I agree there should be a network subforum. Some stuff is just not related to BP or C++.
Nope, at least not from Epics site. Maybe a custom Master Server. But in the End you need to get your hands on Subsystems like Steam.
As for the multiple Subforums for Network: I’m against that. MOST stuff that belongs to multiplayer is either C++ or BP and there you will place your questions in.
If you have questions about network that goes beyond UE4 C++, then you can either use the general discussion or still go C++, because in the end you will need to
connect it into UE4 anyway.
Multiple Subforums just for Networking would be a bit too much. At least in my eyes.