That’s strange. If you run through the help page for 603 - https://www.virginmedia.com/help/virgin-tv-error-codes/603 - it recommends you contact them. Unless you have tried already this would be the last step to resolving this issue. Keep nagging! If you have already done this perhaps it’s time to switch provider.
Tried it again last night, no On Demand except for anything on BBC iplayer? As you say, very strange.
Powered the box down and then restarted and everything back (for now).
I have not contacted Virgin but have run through the 603 Error help pages withy no joy. Incidentally, live and recorded 4K material through the box from Virgin Ultra and BT Sport Ultimate plays perfectly at all times, as does any 4K content on iplayer.
The TV is a Samsung Q90R (2019) on which all HDMI ports are HDCP2.2 compliant.
If this is an HDCP issue, then it should either work or not. If the error occurs "randomly" and is solved by a restart before "randomly" recurring again (in a repeating loop) that would tend to suggest software bugs IMO.
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