@Steve.H 

Hey

If you have purchased the v3 version it came out in 2020 so should be supported for a while yet.  It had it last update in Oct 2021 but home grade equipment doesnt get updated as much as business grade so that's not unusual.

In answer to your question, I had BT FTTC with the Smart Hub and one of the first things I done was to replace it with the VR400 (your ones little brother) and this worked flawlessly for 3 years I had it...    In terms of spec, they are similar if honest, but personally I have always had better results with non ISP hardware, the BT hubs are grand... but perfere the TP Link stuff

If its resyncing the line however, that indicates its detecting a fault and going to fail safe speeds...  its worth a try changing it tbh but not a guarantee

@Philbert Yeah it's the V3 I have ordered.

At this point I'm just trying everything I can to get a stable connection. I have had Openreach engineers out countless times and they always tell me the same thing, they can't find the problem. The issue is it's a very intermittent fault, my connection can be perfect for weeks but then go to hell and drop constantly. I have replaced the network card and all the cables, so I figured why not try a 3rd party router.