We are doing some router upgrades over night (actually started this morning, sorry), around 3am to 4am. As usual, should have little or no impact.
The work has not quite gone as planned, and so we expect to do some more work early in the morning during this week, but probably later than than originally planned 3am. We expect there to be little or no disruption to normal services. The issue is not with the upgrade itself but with out automated scripts for performing the upgrade.