You’re right. I just gave a very simplified answer. VLAN isn’t part of the default network communication and therefore every „node“ needs to support it and be correctly set up, or otherwise the VLAN tag will be removed at that point.

And in my other comment I emphasized, that my main issue with multiple WAP is, to distribute the amount of devices each has to talk to. Multi SSID wouldn’t solve that

Since VLAN isn’t officially part of the standard, you’d need all your network devices support it. And I wanted to give a device-load-balance. So not increase coverage but reduce the amount of devices per AP. Separate SSIDs and VLAN aren’t helping that it just makes it easier to track, wich group is causing the load

The main issue is your 30+ Wi-Fi devices. One AP can only handle this much total bandwidth. But first, it looks like you waste 2gb of your fibre speed? Get a compatible router.

For your setup it almost looks like you’re better off with a total 10gb internal speed. And get 2 more AP, one dedicated for your smart home, one for „less important devices“ and use the ASUS for the rest. - remember to use different channels on each AP.

So in short hook your HV,NAS,PC,[new router w/ AP?],[AP2],[AP3],[AP1?] on a new 10GB switch. Split your devices over the 3 AP, on different channels

Edit: or you could get one of those for cheaper „Qnap QSW-M2108R-2C“ That is a 2.5G with two additional 10G ports so you could plug your new router into one of them and use the other for later use of the NAS if it supports that speed