My Archer VR600v v2 usually works on a German O2 DSL line smoothly. However, outgoing calls are sporadically not possible. A busy tone is heard even though the called party is not busy. If that happens, "A flash writing operation is suspended by VoIP" is logged by the router. The problem is not restricted to calling one particular party, but it persists over a certain time for any number that is dialed. Without any activity from my side (such as a restart), the problem disappears at some time, and comes back without any apparent trigger.

My first guess was to look for a problem with the service provider, so I checked the users forum there, and immediately found a tread that fits quite well to the problem I'm observing (unfortunately, I'm not allowed to place a link to the thread here). According to the postings there, the problem seems to come from the router and not from the provider. Does anyone have an idea what could be done to resolve the issue? All the workarounds discussed in the O2 forum do not seem to solve the problem permanently.