When I used mudfish in the past, it worked fine. Then I changed data plan to subscription, and I was frequently disconnected from the game server. The status for mudfish network was sometimes “No Internet Access” and I couldn’t connect to internet. But when I closed the mudfish program, I could connect to internet again. I don’t know what is the cause, my internet connection or the mudfish server itself.
You didn’t use Full VPN mode at all, right? Please confirm it because depending on the use of Full VPN mode, my answer could be different. If you didn’t use Full VPN mode before, it’s very weird because we couldn’t connect to the internet; looks like your network adapter encounters hang or DNS resolver doesn’t work properly.
Done. 
And I’d added some mudfish credits too for testing purpose. If you’d like to change the data plan again, you can do it whenever you want.
Thank you very much.