It can be a good idea to mentatlly seperate your router needs with you 2.5G speeds and WiFi needs, they dont have to live on the same device. For you private lan you need a router so you can hide and control your devices behind NAT and firewall. For that I’d just recommended one of the small hap or hax devices that suits your needs for routing, and/or wifi. If you want to be fancy the RB9005U could maybe work with your switching need as well.

You don’t need Vlan. I believe it is not what you think it is. Vlan is if you want to segregated your own lan int to different independent lans with various firewall rules.

All you need for your dorm is NAT. But for the love of god make sure that you dont connect your lan with the dorm lan or your DHCP server will start handing out IP’s to everyone else in your dorm and it will crash the dorm router. The ethernet jack in the wall of your dorm (I assume that’s how it works for you) needs to go to the WAN port of the router. But bare in mind on mikrotik you can configure the WAN port to be any physical port you want, but with default config it is port 1.

I have done this before as well when living in a dorm where wifi was shit so i did my own little setup in my room so I could stream to Crome cast etc on my own trusted lan. Get a small router with support for wire Guard vpn (i love mikrotik for this) and you have an easy way to tunnel out for all your devices.