Selected Zen due to better uplink speed 500/250 as we need UL. In fact we see 500/990 (CityFibre) so all good.
No problem with install or setup. Tech support answer phone, and know what they are talking about.

They could not tell me how to have my Cisco rv345 as router with ppoe settings, while still have Fritz box as digital voice hub, and the answers on the forums are poor.

The answer however is to configure the Fritz box as a router with the WAN set as simple ethernet, connect it anywhere in your network on ethernet and the digital voice works fine, without the Fritz box being involved in any internet activity at all (other than a router dedicated to digital voice). So now sits in network rack acting as DECT gateway.