I've been getting these speeds consistently since it was installed about 6 months ago but, at the weekend, I switched off the router, modem, server and all the other computer gear I have here and had a few days away...when I get back I find that I can't access WiFi and I couldn't access the router because it had reset to factory defaults.
I'm now online again after setting up the router but my speeds are consistently terrible. ie.

Sometimes I can get around 60mbps at the expense of very high ping but it is often much lower.
When I first set up my router for use with BT I found some settings online with recommended values....I haven't been able to find them since. I'm convinced that these 'performance' settings helped me to keep a great connection as they were slightly more involved than the two-step process I've gone through this time. For starters I manually inserted the primary and secondary DNS.
Does anyone know of any threads which list recommended settings for the 7800n?
Also, is the factory reset bug a common problem? I notice another thread discussing it.