Thanks for the replies. So 5g provides the fastest speeds for the wireless node to receive. My tx power is set to performance, I did try reducing it hoping the bands range would get smaller and therefore not overlap so much but it wasn't noticable. I also kind of need the range for my main to reach the backyard. It was weird tho I remember when I tried changing it to fair my router that's using the powerline went down for a few seconds. Right now I'm only using ipv4 dhcp for stability, but I'm thinking of also enabling ip6. I don't really know how to setup individual aps. If I did, would that mean I would no longer be able to use the app to see how the network is doing? Using bridges for ap, doesn't that require an ethernet connection? I use one to feed net to the ps5 and PC but I cant use ethernet down the property. Powerline connection is full green, node says ethernet backhaul. Also wondering if I should use that speed meter that lets you prioritize connection priority to streaming. One person uses an android box to stream news dunno if that would be considered streaming since it's not an official app. All these routers form a line, the wireless node being closest to the street. Roaming assistant doesn't have any effect as far as I can tell, I did read it only works for aps. Anyways should I enable ipv6?
Wireless bridges are just like a wireless cable. You plug the one on one end into your router, the one on the other end into the local AP, and the connection between them is wireless. Similar idea to what you're doing with aimesh but much better range and more reliable (plus it doesn't share the frequency with clients, it is a dedicated link). Your APs and router will only serve clients at that point, not the connection between the APs/router they will think the connection is wired at that point.
IPv6 won't help you, just add complexity and confusion. Only reason I can think you'd need it is if you have CGNAT and your PS5 is complaining about it. It won't change anything with your local connectivity.
Roaming assistant works on both routers and APs, but you need to set the sensitivity. You can try -70, then -60, then -50, those are a good few ones to test (-50 will kick a client off before -60 or -70 will). In some extreme cases you might even go to -40 but that is likely to cause some problems.
Also make sure "universal beamforming" is disabled on all 3 devices on both bands, that can cause some problems, never really worked well. Also ensure airtime fairness is disabled. It is by default but double check.
Basically, sharing one band for both clients and backhaul (especially when Asus forces them to all use the same channel) is problematic. On the newer tri-band routers, they let you dedicate one radio for the backhaul which is better, but AiMesh still has its limitations. Ubiquiti sells wireless bridges relatively cheap (cheaper than replacing all 3 routers). That is what I recommend doing to people in situations like yours.
QOS might help but if you have a poor connection (just because the powerline adapter is green doesn't mean it is getting high speeds), you really need to resolve that. QOS may work as a bandaid if none of the above is an option for you, but you need to test the speed that each link is getting then set the QOS limits to be below that. None of that will help if you're having issues with wireless clients either not roaming or having signal issues though. QOS doesn't do anything for that.