Duo to Duo Backup Hangs

Hi!

I've had my 2 ReadyNas Duo v1 NASs (RAIDiator 4.1.14 [1.00a043]) backing up from one to the other nightly without issue for the last several years.  The units are at different locations with Comcast serving the source and Sonic.net serving the target.  All these years, the backups, however large they were, finished within a few hours.

After some recent Comcast issues in my area, the backups stopped completing in time for the next one (i have them scheduled for 2am every morning).  I've tried aborting and restarting the jobs with no luck.  However, if I moved the target to the same LAN as the source, the jobs would finish within a few minutes.  I've had failed WAN backups, followed by successful LAN backups, followed by failed WAN backups, followed by successful LAN backups, followed by failed WAN backups (my current status).  I have not had a successful WAN backup since the Comcast issues started (and presumably have been since fixed). 

I'm trying to troubleshoot this and have a few questions:

• anyone heard of Comcast or any other ISP blocking rsync traffic?  thoughts on how to circumvent this?
• I cleared the logs before my most recent over-the-internet backup, and have been monitoring them while waiting for the backup to finish.  The log in Status|Logs|Download all logs is empty, and the log in Backup|Backup Jobs|View Logs seems to be stuck on line 4359 (deleting a particular folder).  There was a very large file (5gb) in the log 200 lines up, that got copied with no issue.  Any thoughts on what it means when the log stops updating?
• Any other culprits to check out or options to consider?

I'd very much appreciate any feedback on this.  Please let me know if you need more information.

THANKS!!!

Sandheep