I recently bought a video entry phone system for my house.  The outside door is about 20m from the house and has a mains power line and signal cable connecting the entry phone to its indoor unit. If I can get internet to the entry phone, then it has an app and I can see who is at the door, and open it, using my phone.

I am thinking to use a TL-WPA4220KIT powerline set-up using the existing mains cable to get internet from inside the house to the outside door.  But inside the house, I can't get the indoor TP-Link unit anywhere near the router - and anyway, the house power is three-phase and I can't be sure that circuit near the router and outdoor cable would be on the same phase.

So I am thinking to get a wi-fi extender such as TP-Link RE220 AC750 and plug it in next to the WPA4220 indoor unit, with a short LAN cable to feed from the AC750 into the WPA4220, then through the mains cable to the other end in by the outside door. Is this the right way of thinking, or is there an alternative single unit that will both pick up the wifi signal in the house and push it into the mains cable, without connection to the router?

Thanks