I'm currently engaged with AVM support to get this support made official. I've tested a couple of proposed configuration updates for the 7390 and will soon begin testing the 7490.
Some initial feedback:
- The Fritz!Box 7390 can support YouView Extra Channels only when using the built-in VDSL modem, not when using the Openreach modem.
- The Fritz!Box 7490 should support either configuration.
I'm continuing to test and will reply to this post when I have any news.