How to make use of old TV wallplugs and RJ11 phone plugs?

Hi,
I have quite a big house and the electrical installation is very old. There is a complex installation of inwall TV cables spanning 2 floors and distributing the house from front to back. Same for RJ11 phone wallplugs (two opposite rooms in 2 different floors + doorbells). I am wondering if I could take advantage of this existing wiring to plug interesting connected devices?
I’m renting and I am not planning on doing heavy inwall electrical work.
Thanks for your ideas.

PS: I’m a newbie, sorry in advance for the misuse of certain words.

You can use MoCA adapters to connect your existing coaxial cables. Just be aware you will need one to connect your router and another at each room/endpoint.

If you mean coaxial cable, I highly recommend Moca adapters. I have 3 in my home and they have been rock-solid.

They don’t work across some splitters and you probably have no way to know where there might be splitters in the wall so it might be a leap of faith to purchase and see if they work. If you need to add a splitter, there are ones that are Moca-friendly.

Thanks. Stephenn and Diggeridrew.
About splitter, I am pretty sure there is only one, which is apparent (in a box outside the wall in the garage). Then, I can follow (with naked eyes) the cable paths all the way to the plugs (so I guess it’s not completely inwall, but the job is cleanly done, I don’t want to ruin that).
What worries me most so far is the price. The cheapest set of 3 that I found on Amazon FR are the Starlink ones.
I’d rather buy another Devolo PCL instead, and forget about the Coaxial, if I need to spend that much money.
But I read the technology is actually overpriced and my skills at cutting wires are not so bad. Could I build one myself?

What about using this wonder of technology :wink: : ZBMINI-L2 - SONOFF Official
Can I make the coaxial plugs “ortho-axial” and recover individual wires ? (I start talking about thing I don’t understand, but let’s try)

I misunderstood; I thought you were trying to distribute your home network and that is what Moca adapters are for. They won’t help with smart plugs and the like as far as I know.

I don’t think you misunderstood. You’re idea is more than valid. I’m actually open to any suggestion to benefit from this cable work going through my walls.
The only limit is the budget. I actually liked this idea of CoA to Eth as my ISP box is upstairs, but my cluster of RPis is downstairs and only wired through Ethernet from the Devolo CPL adapter. So if I can make more Ethernet plugs, that’s great.
I had dismissed this in the past because I wanted to convert RJ11 to RJ45, but someone explained that I’d never get the desired bandwidth. Never had thought of MoCA before.

Good to know. In that case, these are ones that I have:

https://a.co/d/eymG5MK