Not trying to stir the pot or anything, but your WinMTR log posted here clearly shows that the very first hop after your router experienced not only a small amount of packet loss, but very high latency spikes. Both loss and high latency spikes are not good for maintaining a connection in Diablo 2. The game has always been sensitive to both packet loss and high latency spikes with the end result usually being disconnection from the game.
I have a very stable connection which is literally three hops away from the largest backbone in the United States. I have had very few issues with the game relating to loss or latency. I recall a total of three times that I’ve been disconnected from the game, and that’s since the game was released.