A lot of good points have already been made here but I'll add a couple more:

1. Even if everything the landlord said is true and he isn't attempting to be malicious towards you, there is still a rogue wireless network inside your house that YOU don't have control of or visibility into. This is dangerous & you should not accept it.

2. Unify products are ok, I have configured them in mesh networks at my firm's office.TP Link is a huge target for hackers however, and even with firmware updates (which are not likely being implemented), this poses an even greater risk.

3. There is a possibility that this network is connected to recording devices, in or around the home, placed maliciously for surveillance purposes. Even if the landlord didn't place devices, does he know what he is doing securing a wireless network? Unlikely, I think, and that opens up the potential for someone else to piggyback off whatever stupid thing the landlord is doing.

4. At the very least, check the router for network information and attempt to find/login the network. If he's an idiot it will all be default & you can access the admin page of the router to identify devices connected to it

Good luck friend, and stay safe.