I run a small family server via a hosting service. If i try and AFK something from my PC, i regularly get disconnected after a random (but relatively short) period of time. usually 20-40 minutes after i walk away. My son (on same network) can stay connected for DAYS. It's consistent enough that I know its something happening only to me. It doesn't do it while I'm actually playing, only when I leave the PC. At first I blamed it on my computer entering some kind of "sleep" mode, but every once and awhile it will stay connected for hours, and i'm doing nothing different.
This is the message that I get on the servers console "(player_name) has disconnected, reason: Internal Exception: io.netty.channel.unix.Errors$NativeIoException: syscall:read(..) failed: Connection reset by peer"