I've got a remote location in which I installed tens of wired Ubiquiti AP supporting both 2.4 and 5 GHz bands.
I a couple of rooms where I can't easily extend current cabling, I have some weak Wifi signal issues.
Previously, I had some successful experiences using Alpha Network WiFi USB adapters.
Once, a PC that couldn't connect with native wifi using 2.4GHz could connect through Alpha Network USB adapter through 5 GHZ band !
Unfortunately, these adapters only work with PC and they require software downloads on client PC.
That's the reason why I'm looking for an OpenWRT-compatible router that will work as a repeater/extender/whatever, connecting wirelessly as a WiFi client while simultaneously offering a local WiFi downlink.
Ideally, for a better throughput, both uplink and downlink WiFi should work in 5 GHz (if radio conditions allow it) but in different channels. I don't know if devices with dual 5 GHz radios exist. If not, I think I would use 2.4 GHz for uplink and 5 GHz for downlink to avoid interferences.
Ubiqiti Nanostaton 5AC loco is a small CPE with a strong directional 5 GHz system and a secondary 2.4 GHz radio that is intended only for short-range connection for configuration. It can serve a laptop etc that is close to the device. The list price of USD $49 is well within your budget but many sellers are charging a premium from short supply.
support for D-Link dir-3060 seems recently added, but I dont have it, so I dont know, if both 5GHz units are supported.
Not sure, if 2x 5GHz will be the holy grail in all cases. Depends on the typical distance in your vicinity:
between client and repeater
between repeater and Wifi base AP
if you are opting for repeaters, you are planning for long distance, then superhigh throughput will not your friend anyway. If you want reasonable throughput, you need cables.
e.g. a 5 Ghz MT7621 AC AP right next to the client has up to 6xx Megabit/s, but in a distance can easily drop to 50-100Megabit/s.
You need to try: Depending on which of the two distances is larger, connecting client via 2.4 and backhauling via 5 could turn out better or the other way round. But there is no guarantee that 2x 5GHz units in comparison will be better per se without testing it.
Unfortunately, I can't use Powerlan over there (source and destination not on the same electrical grid).
I didn't know tri-radio devices existed. I've look for the Asus Lyra AP-AC2200 but it is not available anymore. In OpenWRT Table of Hardware, there ar not many devices tagged with 3wnic.
I bought one GL-B2200 Velica which is OpenWRT based supposed to have tri-radio.
I'm aware it won't be a magic bullet given how fast the throughput decreases when a repeater is moved away from AP: if 5GHz is non-practicable, I'll try with 2GHz.
I'll report here my findings when I'll receive this GL-B2200 Velica device.