Lets deal with this logically. Your router and Asus AP are relatively ancient, the N66U is something like 12 years old at this point and it’s no surprise the wifi is flakey, its very surprising it still works at all tbh. Consumer routers with 8 ports are just not a thing, the reason for that is it’s about a tenner to buy a switch, and people who want more ports do that rather than everyone paying for extra ports they don’t need.
How much do you want to spend? Amplifi is essentially a dead end at this point, but still has a resale value for those invested in it/in denial. VM also over provision connections by roughly 6%, I can’t remember what the ERX tapped out at, but if you are OK with whatever it’s doing, then who am I to argue?
Flint2 (£120) - OpenWRT based (like the ASUS) but with massively more CPU/RAM/better wifi and the option of running a vanilla OpenWRT build, so not tied into a commercial lifespan, it will be supported for as long as it can be.
Unifi Express (£120) - It’s Unifi, but without IDS/IPS, includes a Wifi6 AP, 1 port LAN though, so needs a switch.
The UCG Ultra is cheaper (£90), has IDS, 2.5Gb WAN and 4x1Gb LAN ports, but no AP, this would be my preference, wifi probably being as many cheap NanoHD’s (£40-50) as you like. You could also go with a Mesh option, but make sure you hard wire the nodes.
Switch wise, TP Link metal enclosure units tend to be my default, they are inexpensive, work well and last longer than Netgear etc.
All of those are based on what you have said you are used to rather than the steep learning curve of trying to manage a Mikrotik (though that has got a lot better in recent years), other options are also equally valid, but its up to you how much you want to re-learn.
