Zend certified PHP/Magento developer

NAS disappearing

Dear fellow superusers please help save my sanity.
This is a network question and I have no idea if this is the right forum.

I wanted to get into Ubiquiti as easy as possible so I bought 2 unifi 6 lite AP’s and a lite switch. I have kept my ISP router/modem and turned off Wifi.

I have pulled a lot of cables to get as many devices on ethernet as possible including my NAS from Synology. Wifi works, cables work. For some reason I can’t access my NAS from wifi and it’s driving me nuts.

I have a lot of parts where things can go wrong, but I can’t find anything not working. My NAS is wired through: Router -> Lite switch -> wall plug -> TP-link switch -> NAS.
I find it super quick with ethernet. On wifi it just hangs.

I have no idea what setting to test or what to try now. Please advice.