How do I get WiFi and phone service, technology in the basement

Will I have problems because of the different manufacturers?

No, of course that works without any problems.

In my example, it was about when the FB also broadcasts WLAN. In that case, it makes sense to set up the FB repeaters as access points as well, because then FB and access point broadcast the same SSID and negotiate among themselves which connection point is best for the client. If you want the FB to broadcast a WLAN and use the Unifi as an access point, you must either use different SSIDs or give both the same SSID, which will inevitably cause problems for clients because they won't know with which of the two they should best connect.

Only use one manufacturer for Wi-Fi, because these pseudo mesh standards are not cross-manufacturer.

Router AVM and access point Unifi of course works and has been running smoothly for me for some time now.

My plan was actually to combine Fritzbox as a modem with Unifi lite access point(s), phone also through Fritz. Will I have problems because of the different manufacturers?

No, but be sure to deactivate the Fritzbox's own Wi-Fi network.

No, but definitely deactivate the Fritzbox's own Wi-Fi network.

That is the plan. I have even understood that by now, thanks to reading the forum.

When it comes to Wi-Fi, only use one manufacturer because these pseudo mesh standards are not cross-manufacturer.

But if I stick with AVM (router and repeater), then the mesh standard should solve the problem of switching, right?

No, but definitely disable the Fritzbox's own Wi-Fi network.

Why turn off the FB’s Wi-Fi? Sorry, I haven’t come across that yet, but I’m also not that deep into it yet.

But if I stick with AVM (router and repeater), then the mesh standard should solve the problem of switching, right? Why turn off the WLAN of the FB? Sorry, I haven't come across that yet, but I'm also not that deep into it.

Turning it off refers to the use of other ACs than those from AVM. As for mesh, with AVM you have to distinguish whether the additional WLAN transmitters operate as AC or repeater. It certainly makes sense to use mesh with the repeater. With the AC, I think you can't even activate it. But I'm not sure. We had ours running purely as an AC in bridged mode.