Both work perfectly with a 7530 router from AVM and that is because AVM are a worldclass provider of routers.
???? What have you swallowed? Your printers should work with any old ethernet port.
The Linksys SPNMX55 that Gigaclear supply is limited to wi-fi cinnections
This I don't believe. I can't see Gigaclear disabling ethernet ports and I can't see your landlord doing it either.
Your problem most likely is a straight configuration problem. How were these printers set up on the LAN previously? DHCP or fixed IP? You need to get them on to your present LAN IP address range either by fixed IP or by DHCP and in the latter case you need to then find them on your LAN.
You will need the app - unfortunately, I think this router requires an app rather than using a web interface - and you will need the router credentials from the landlord to be able to see what is going on. Yes, these things should possibly auto configure, but if they are not, then you need to be able to see what is going on.
I can assure you that I have not swallowed anything.
It is NOT a 'straightforward DHCP problem'. I do have the Linksys app. There is an option 'Add device'. Three options - computer, printer etc. All three options are Wi-Fi only. There is NO LAN connection offering. And YES Gigaclear/Linksys do not not support any 'normal' LAN connectivity on those ports.
What you can do, however, as I discovered yesterday, is to connect LAN1 on my Fritz router to one of the Linksys's three remaining ports. Setting my Mac to use the wifi from the Fritz router I can still access the internet. But more importantly, I can plug in my printers to any of the ethernet ports on the Fritz repeaters or Fritz router and they work fine.
So sorted. Now for that audio.