I need to add to this as I am having same issue since this firmware update. My router is syncing at the speeds it used to but wired and wireless devices are not getting speed they should.
Everything was fine until this update. Someone must inform BT ASAP. This is a strange fault.
Thanks for your post and welcome back!
Sorry for the problems you're having with your throughput speed. Are you still having the same problem today? Post back and let us know what exchange you're connected to and I'll check for any potential issues in your area.