We haven't played Minecraft for some time because we've had connection problems with my son's remote private server. After launching and trying to enter a multiplayer game on his server (Internet, not LAN), the world would load and work for a few to 10 or 20 seconds, then spontaneously disconnect. We tried various things - none of which I recall since it's been a while - but eventually gave up thinking it might be too slow a connection (2 Mbps). This is on a 4-5 year old Win10 desktop computer.
However...today I tried it on a new Win10 laptop, with the same Internet connection and it worked fine.
Any suggestions on where to start trying to find and fix the problem? Any additional info needed?