ATT router/AP <-> SXTsq 5 ac (acting as upstream interface/router) <-> nw switch <-> unifi u6-lr AP
Yes… something like that would be a good start.
The directional antenna in SXTsq 5 ac will allow for more sensitivity and signal strength, thus making up for some of the losses due to the wall and distance. I’m guessing you might get 250-300Mbps clean through?
The RouterOS in SXTsq 5 ac isn’t that bad, it supports VLANs for guest networks and so on, supports setting arbitrary DHCP server options, and can do Wireguard and ZeroTier, and some light weight scripting. The IPQ4018 is old 40nm Cortex A7, but it’s got hardware AES and Mikrotik usually cuts out packet processing compared to traditional Linux kernels.
You can offload all the routing to pfSense opnSense OpenWRT vyos or whatever random distro whenever you want on the future sand can configure Mikrotik to just pass packets if you so wish.
Your own dedicated AP further down the line, will allow your devices to run on a wifi channel different to your neighbor’s , and your devices won’t compete with your neighbor’s for airtime because you’ll be able to use different frequencies.
U6-LR can actually run OpenWRT… sooo in case you’re ever curious… that’s one more toy.
On a more serious note, I’m routinely getting 800Mbps+ over WiFi with it with my phone, so transferring files between your laptop and your home network should work well enough for your own needs.
As a switch, how many ports world you need? You might want to consider a POE switch which will power your Mikrotik CPE, and your unifi access point.
If you wanted to go fully wireless, you could hook up the Mikrotik to the Unifi directly, but your tiny mini micros should really be on a wired network where they’re happier.