Sky broadband router woes

Here at irrelevant towers we have two broadband connections, one from ukonline, and one from Sky broadband.  (They are both easynet brands, and actually connect to pretty much the same kit at the exchange.)  I have  a router/firewall device that does some basic load balancing between the LAN and each WAN link.

Sky supplied us with a customised version of the netgear DG834GT. Part of their customisation is to make the router poll for firmware updates, and install them automatically.

The other day, it updated.  And broke that internet connection. The firewall could connect out to any internet host it liked, but not any of the LAN based clients.  It seems that there is an issue with it routing incoming packtes according to the user specified routing table.  Or maybe their firewall settings are too agressive.  Either way, replies to packets sent to it from outside it's immediate LAN connection don't make it back to the firewall.

Netgear Tech Support have said to speak to Sky, as it's customised.  Sky, after the usual initial crap responses, have eventually decided to throw a replacement router my way.  It's here and in and working.  On the old firmware.  I'm just waiting to see what happens when it updates.. I'll keep you posted.