@StevenVDM 

Yes, you can. There are two ways: you can create separate WiFi mesh network with just Deco in Student room, or you can add that Deco to mesh you already have.

I am curious, why haven't you considered to buy general purpose WiFi router, some could be found cheaper than Deco M5 unit? Usually, after such router is configured, the only troubleshooting it ever needs is power it off/on, which Student room tenant can do on their own.

Finally, you must realize security implication of home network sharing. Does not matter if it is Deco or WiFi router, if this Ethernet cable from Student room is connected to your home network, all your computers, tablets and other devices on home network will be accessible from that room. If you trust the Student room tenant, it is fine. If not, consider security implications.

  @Alexandre. The student home is at 5 miles from my house, so no DECO m5 is not connected to my house netwerk but at the student residense Internet.

I just think a deco m5 is easier to set up with the smart phone, I don't have a PC on site to set up the router. If something needs to be adjusted on that router, I would always have to bring my laptop or something to set it up. That's why I thought of a deco m5 solution

  @StevenVDM 

No problem, then, to use Deco M5 and you are right about remote management. If you already have your own Deco mesh, in Deco app create new network for that Deco M5, so that you can use same app to manage multiple networks: https://www.tp-link.com/en/support/faq/2295/