This is more for information than anything else. After I installed Avast on Windows 8, I could no longer use the management interfaces for my two ASUS wireless routers (RT-N66U and RT-N16U). After typing in the userid/password, the web browser (Chrome, IE or Firefox, it doesn’t matter) would time out. Other networked devices (Trendnet IP cameras, HP and Canon wireless printers and a Belkin wireless router all worked fine. Adding exclusions in Avast for the two router IP addresses did nothing. However, temporarily disabling Avast for 10 minutes was a successful workaround.
You don’t need to disable all avast shields. Just try disabling Network Shield, you will reach interfaces just fine. It is a known problem with Network Shield.