So, quick update on my new synology-powered mesh network.

It has been working flawlessly for two weeks now. As stable as I could hope for. WiFi coverage has been *quite* solid and performance has so far never disappointed me, anywhere. Essentially flawless, really.

So far, only one issue, admittedly not affecting my specific setup, but still. SRM (Synology quite remarkable router software, managing the entire mesh network -) comes with a "Safe Access" feature/app (optional) that allows to group devices in your networks into groups ("profiles") and set network access policies to each, such as time/date when access is allowed, filters of sorts including parental control, etc.). It also produces activity stats.
I noticed that while ALL devices in my network are correctly detected in other parts of SRM, "Safe Access" does not seem to see some devices. My understanding of this is that "Safe Accesss" will only detect devices that connect at some point to the main wireless Access Point of the mesh network. So, over time, "Safe Access" ended up detecting all devices in my apartment as they did, at some point, connect to the main Access Point, but it never detected the 6 clients in my garage (5 IoT devices to control power drops, lights, EV charging station, and my car Android-based infotainment system). Please notice that such devices are immediately and correctly detected in other parts of the Synology OS. This is a "Safe Access" specific issue.

Since I have NO profile policy in place, that is not an issue for me specifically, and all I have are inaccurate stats, but, it could certainly be an issue in other setups.

Side note:
This simple profile/policy feature in the "Safe Access" app in the OS is quite useful for IoT. I grouped all my IoT devices into one profile, and I have been monitoring them, to happily confirm they are NOT communicating outside unless I want them to. Pretty nice considering setup time of the whole thing was few minutes.