I seem to have a similar problem.
It's a long story. I have fibre to the premises. I changed from BT to Sky for broadband (and land-line) in May. I have a BT Whole Home Mesh system of 4 discs which worked beautifully, and I didn't want to take the risk that they would not play nicely with a new Sky hub. I understood my old BT Smart Hub 2 router should work perfectly well with Sky broadband and if I kept it I would not have any problem about the Mesh system working, and so it proved. The broadband was fine (if little slower than my contracted 150 mb/s, minimum guaranteed 100 mb/s).
What I did not notice until a few days ago was that the landline was not working (we only ever use it as emergency backup). After reading a couple of forum posts, I decided this might be because I was not using the Sky hub, so I took it out of the box and connected it up. The good news was that it seemed to work fine with the BT Whole Home mesh system and so the broadband was pretty good (possibly a bit faster than before). But the landline still didn't work. After 45 minutes on the phone to Sky support and several reboots (including flashing green lights on the hub, which Tom at Sky said was "updating"), they found that for some reason the hub had not been "added" to my account (it did not appear in My Sky app) - so they did that and then everything appeared to work really well. The landline was connected and my ethernet connection to the router reported upload speeds of 149 mb/sec and upload speeds of 300+ mb/sec !
So all was apparently good., but only for a day and a half. This evening, at around 8.25, my Smart TV stopped working in mid-program, reporting no Internet connection. The sky hub was flashing green continuously - a slow pulsating flash. After a load of that, after reading this thread, I decided to swap back to my BT Smart Hub. Unfortunately, it displayed an orange light (meaning no Internet connection), and nothing worked. So I swapped back to the Sky Hub. The MySky app had previously been reporting no local issue near me with broadband generally, and my fibre terminal box has had three green lights all the time (for power, Port 1 and PON), so no problems there.
After swapping back to the Sky Hub, it got stuck indefinitely on the slow pulsating green flash (after a couple of attempts at rebooting) and the MySky app was reporting a local broadband issue "which is normally resolved in a couple of days"! I then called Sky support at 9.02, finding out that they shut at 9.00. So I am stuck without broadband and a very similar set of symptoms to those set out in earlier posts. My Admin pages on the router show DSL Software version A2pvfbK048i. D28d, software image name SR213_7.6p1s2_PROD_sey, and "advanced services" of SR213 (which is the model number of the hub).
After over 4 years of completely reliable service from BT, I am beginning to regret switching to Sky. Reliable broadband is absolutely crucial to my work.
