A surefire fix I found for me and my friend, we went from constant disconnects to none in over 10 hours of play (one session of 4 straight hours included)

Get everyone playing to download Hamachi, its free and you can make your own "network" which everyone connects to, then they connect to you using LAN and your IP.

To get the hosts IP, on the host PC type CMD in the windows search bar, open command prompt and type IPconfig, look for IPv4 Address under "Ethernet adapter Hamachi:" and that's the number connecting players will need.

Once everyone is connected that way, the disconnects should be gone unless someone is having internet problems.