Sorry guys got a little busy and forgot to mention the fix, the fix that worked for me was that after starting the Signalling Servers and Matchmaker server you also need to open the unreal project for each Signalling Server, unless you do that the error doesn’t go away. As soon as you have started unreal projects for both the SS just go to the Matchmaker port using “localhost:90” or “yourpublicip:90” (Personally I find hosting Matchmaker on port 80 much easier since I don’t have to mention :90 each time), you’ll be automatically redirected to the respective port of the available Signalling Servers. Once occupied no more users can access that port, exactly like it should work!
Thanks for everyone, giving their time in helping me! I just figured out since it was working before and suddenly stopped since I forgot the exact steps, so then I tried to replicate my previous actions and it worked.
Moreover this also indicates that the Unreal engine documentation should also mention clear instructions on how to use Matchmaker services for pixel streaming.