Just a follow up to say after a reflash to .94SF and a factory reset. All is back to normal, not sure what happened before but all is looking good. Thanks for the suggestions! :)
After some messing around, I haven't managed to get 5GHz to stabilise and after about 30 mins of booting the router, 5GHz disappears altogether. I've reverted back to v1.0.2.93SF for now and things are performing the way they were. I'll do some more testing over the weekend and see if I can get...
I've just tried transferring some files over to my NAS. With the previous release I was getting around 80 - 85MB/s with a very stable transfer graph, with this version I'm getting erratic transfers between 5 - 30MB/s.
The link speed usually holds 866/866 but I'm also seeing the following...