Hello,
I'm assuming that by "internal exception" you mean that you're receiving the all-to-common error of: Internal Exception: io.netty.handler.timeout.ReadTimeoutException
This isn't an issue with your Internet; this issue has been affecting all users on multiple networks regardless of their Internet speed. The issue? In the 1.7 snapshots prior to the 1.7.2 release, many servers reported that users were being disconnected with the error message listed above. They've isolated the cause to be corrupted data files formed by what they believe is a bug in the way Minecraft servers auto-save and create backups. This would explain why sometimes the chunks don't load; the chunk data has been corrupted.
Our network may periodically experience this issue, but due to the way our server loads map files (ie. doesn't physically make changes/save/backup files in the world), the corrupted data files will eventually be rewritten when a new map is loaded. Essentially, when you break grass/leaves, these changes aren't permanent the next time the server loads the map; it reloads a fresh world containing the map every time.
Unfortunately, as annoying as the issue is, there is nothing that you or I can do with regard to fixing this issue; the problem is rooted in Minecraft itself. We'll just have to wait it out!
For more information, visit the open Minecraft Bug Report concerning this issue here:
https://mojang.atlassian.net/browse/MC-34947
I hope that despite this issue affecting many servers you'll be able to continue enjoying our network! Hopefully I'll see you around! Happy holidays! :]