I dont have extreme lags, and DC is not that often, but same, have DCs with 90000 or 90002.
Myself, I know it come from my router (no wifi, just have some small lose of connexion for 5sec)

My problem with this : Cant reconnect fast after, my character stay online for 2-3min (and sometime ven more), even if I try to reconnect 200 times, wont work till the server doesn't see that I'm not online anymore and kick me.