I recently purchased this dual band router. I notice that my downloadspeed is very unstable. I check my speeds via speedtest.net. I get a max downloadspeed of 40mpbs, but it suddenly drops to 6-8 mpbs.
IME variations in download and upload speed are usually caused by the network provider, not by the router. I saw this more than a few times when we were on DSL. Has been rare now that we are on FIOS.