I doubt it's an ISP issue. I only encountered it briefly yesterday and a relog fixed it. The twist for me: I was dual boxing and it only happened to one character. No idea how to explain that lol
THat happen to me for 2 months straight and it was 2 of my four accounts randomly. After the 2 months of bitching to SE and Comcast it was an ISP issue. Comcast stated it was a “dip” issue where the signal would dip randomly which would not afffect everything. Hence why 2/4 disconnected not all 4 error 4001 I believe it was. As for this issue of random 0s could be data center again.