We just moved offices and have a whole host of macs all on a single time capsule router. Never had any issues until we moved offices but now a couple users on the network are having issues. They have full wifi strength signal but ping/upload/download plummets on and off throughout the day. Doing PRAM, SMC reset seems to fix it for a while but the problem comes back throughout the day. Both machines are 2011 MacBook airs (other MBA 2012+ no issues). I have updated the time capsule to the latest firmware and running out of ideas. No one else is having issues so ruling out ISP related issues. Need to fix this fast, thanks!