I know I saw something about IPS breaking DNS but this is a little different, so I'm posting here. All out bound web traffic was broken, but DNS worked from the command line. Email worked, I could even get Twitter updates. I couldn't find out if it worked from the Astaro as well because I couldn't access it internally (Webadmin or SSH).
I had to launch the SSL VPN client via a different network so I could log into the device. That's right, no internal access to the Astaro only external, glad I set up the VPN and added it to the allowed networks for Webadmin.
I switched off the proxy and could browse and access the Astaro internally, until this morning. Same symptoms again, no web traffic or access to the Astaro internally. Checked here and saw the IPS breaking DNS thread but putting in DNS locally didn't work. I had to connect to a different network (thank goodness somebody didn't lock down their network [:P]) launch the VPN client again and logged into the Astaro and switched off IPS. Everything worked, turned on the proxy, and it still worked. So far so good, if it dies again I'll re-post.