Hello, would like to give you on how to resolve your disconnect and lag issues, I mean it worked for me instantly so I prefer to tell you how even if I didn’t confirm it with other players. Atleast it could work for some.
So let’s get started, first thing first I opened the ports 80, 443, 9405 and 9505 in both my router and firewall configuration window just like it is said in a MTGa support thread. BUT the catch is that you actually have to unauthorize mtga in your firewall and authorize the new rule with the 4 ports opened (letting both of them authorized didn’t resolve the issue for me).
Hope it will resolve your issues.
Good luck in all your future games.