Hello everyone, this is my first post here, I already know that there is limited support for my router, however I love OpenWRT and I love my router too, it's been reliable since I bought it and I have no plan on replacing it for now (limited budget recently thanks COVID).
However team, is there a USB dongle supported by OpenWRT that I can plug in to my router so I can cover that missing part of no WIFI by providing wireless access thru the dongle since there is no WIFI support yet?
There are no good USB wireless cards suitable for AP mode and 24/7 operations. Performance and range would be horrible thanks to the tiny antennas (which tend to be too close to each other for MIMO to be effective as well).
Have a look at second hand wireless routers, sometimes you can find incredibly cheap offers with good specifications. The ipq806x range of devices would be roughly on par (surpassing) the features of your rt-ac68u, as would mt7622bv+mt7915e - ipq40xx or mt7621a would be slightly below your current specs, but might still meet your current requirements.
Walking on a limb, based on your nick, the https://openwrt.org/inbox/toh/askey/rt4230w_rev6 can be found starting around ~20 USD on the North American used markets, providing top specs (ipq8065+qca9984).
Netgear A6210 USB 3.0 AC1200 WiFi adapter based on mediatek chipset and is supported according to previous posts, one of which is here: Openwrt x86 Netgear a6210 AP mode how to There are other threads which go into more depth to confirm it works but I am lazy and only c/p the first one to come up....
I researched this enough that I bought one on amazon for $20 used with stand and 1 foot extension cable and am waiting for it to show up. If OP is interested I will update thread after it arrives and I give it a good thrashing. And oddly enough it's going in the back of an AC68U as well. One nice thing about the A6210 is that the junky collapsible panel antenna is actually removable and is connected with u.fl connectors so if one would wish they can get u.fl to sp-sma adapters and use 2 of the AC68U's stock external antennas on the R6210!
Op, what are your intentions with the AC68U? Mine is wired only and used as a router+nas and for this it works well. Esp when overclocked but I got that Netgear A6120 WifFi adapter on order for iot isolation as well as guest WiFi isolation.
BTW that RT4230W sure looks yummy but they are about $40-$50 on ebay and much much more on amazon. where to get for $20?
Even if the driver is pure gold, the performance and reliability will still be… 'sub-par' (to keep it PG-13) with any USB WLAN card. Even a cheap (bad) router runs circles around any USB WLAN card, for simple physical reasons of antenna design and Mu-MIMO. There is a reason why high-end routers are bulky and/ or look like upside down spiders.