Question Having a weird black screen problem on a steam game

Jan 23, 2021
So few days ago I shifted to my new PC and I installed Blood of Steel from the steam store. Now after the launcher starts, after I select server, the screen goes and then after few moments, says disconnected from server.
Now, I did some testing. The problem is occurring when I use my broadband connection, since I can play fine on another 4g connection, but here's the weird part, I can play blood of steel fine on the same broadband connection on another laptop. I also tried connecting my broadband to a laptop, then enabling hotspot and via wifi receiver on pc, i tried connecting but i get the same problem, black screen then server disconnected.
The more weird part is, if i create a new steam account and then log in blood of steel, I can then log in and play for few hours, but after that it as well shuts down and am back to black screen problem. Tried contacting support for the game, but they can't really nail this.
The problem occurs only when I use this broadband connection on this very PC.Tried disabling firewall as well to no avail.
But if i use the same broadband connection to play blood of steel on my old laptop, it works fine,no black screen and such.
Am really so frustrated by this problem,please help me.