So, at last got around to manually installing the "fixed" Oreo firmware on this TV - been running the original firmware since owning the TV because of all the little issues.
All seemed to be fine for the first few days, now I'm randomly getting "Ethernet cable is disconnected" messages appearing on screen.
These were initially appearing whilst using the SkyQ box or the PS4 Pro - so not an issue, however it appeared last night whilst we were using Netflix and of course that all halted and the only option was to reboot the TV.
Thinking of it as a one-off we continued - same thing happens an hour or so later.
Doing some digging around, the only fix being offered by Sony (via forums - doesn't appear to be official) is to turn off IPv6 at a router level - there have been a couple of people reporting this as a fix, I'll be trying this later (I do hope this can be disabled via the Sky routers).
I do rate the Sony TV's as a TV - their LED's even now rival OLED at every point, but boy - do they firstly give up on older TV's quickly...stopping software updates and how they can continuously pass QC with some of these software builds I just don't know.
Obscure problems I understand. Everything cannot be tested before a build goes live. But surely, having the TV on an IPv6 network would have been something tested before it was released?