Error 603 is generally due to the HDMI cable not being HDCP2.2 compliant or if using a switch to connect HDMI devices that either the switch itself is not compatable or one of any other HDMI cables attached to the switch.
Do you have Ultra HD 4K TV's? If so ensure the HDMI cables are HDCP2.2 compliant as above, also try connecting to different HDMI ports.
You should reboot the V6 each time you change ports or HDMI cables so the changes are recognised.
If the TV(s) don't support HDCP2.2 then you need to change the video settings on the TV box to output in HD.
SelectHome and Settings
SelectVideo Output Format
Untick the box2160presolution and make sure the1080pbox is ticked
Press Thumbs Up3 times to save the new settings
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Like you, after weeks of frustration and trying absolutely everything advised, I cured it by rebooting to get "On Demand" etc. working temporally and then immediately changed the V6 Power Setting to "Always On".
The problem seemed to be when the box came out of either of the "sleep" modes.
Undoubtedly Virgin will recompense us for the small amount of extra electricity used in solving this for them! 🤔
Thanks japitts Thanks also for the Newbie help! I have bought several leads and none have cured it. I have also dropped the output to 1080 in the past. I am going to try to leave the V6 box permanently on as someone else has suggested. Digidoug1
Hi Digidoug, It took me a few power downs, (i.e. turning off at the mains) to get on demand working again temporarily, I then changed the power setting to "Permanently On" and all OK since. I am on a couple more forums and people report it has worked for them? Strange?