I am also experiencing the same issues that many people have reported on this forum - as soon as I start an upload of almost any size the wifi drops and/or the router freezes. This is guaranteed to happen 100% every time files are being uploaded. I would appreciate it if BT could get in contact to resolve. I have the BT Ultrafast Router and the Firmware version is SG4B1000B540. It seems that people are reporting a firmware version upgrade performed by BT seems to resolve the issue. Many thanks.
I have asked a moderator to provide assistance, they will post an invite on this thread.
They are the only BT employees on this forum, and are based in the UK.
The issue will need to be raised with the Ultrafast team as a fault. They should be able to get it investigated for you quicker than we can as we would contacting them for support. The Ultrafast/FTTP team are the only ones trained to be able to fix it.