I designed a router board, to use it in combination with the USB MT7610u stick
It was the smallest solution for Gigalan and Dualband.
From the tests everything was perfect, now MT7610U is no longer in production.
I bought all the dualband sticks that I found, but none are recognized.
Don't exist drivers, or I don't understand which driver does it require.
ar9721 is 802.11n and 2.4 GHz only, while the ath9k_htc isn't bad, it's unsuitable as AP (not reliable, weird connection stalls, 4 (or 8?) connected clients at most). It doesn't make sense to buy an almost 10 year old device today.
That is the Main Menu. If you go to menu item 2 and scroll down to the section on the mt7610u chipset, you will find several adapters based on the mt7610u.
It might help if you explain in more detail what you mean by "very small". The Linksys AE6000 is very small. I have one. It works well and it is very small. It is only slightly bigger than a nano size adapter.
The mt7610u adapter that I use with my OpenWRT setup is the ALFA AWUS036ACHM. The size does not matter in my case because it comes with an extension cable so I can place it where I want. This adapter has astounding range.
If your use case could work with an extension cable, then you might even look at an adapter based on the new mt7921au chipset (WiFi 6e). The driver is in 22.03... 7921u, however the firmware is in the driver 7921e so you either have to also install 7921e or manually install the firmware. There is a bug posted requesting the firmware be moved to common so this will likely be fixed at some point.
It may no longer be in production by the Chinese copycats but it is in production. That doesn't matter if you can't get chips so our discussion on whether it is in production does not currently matter. Mediatek is still producing chipsets as far back as the rt5370 single band chipset. They have retired the re3070 and rt5372 within the last year. Being a fabless company has some downsides. I saw where Mediatek signed a contract recently with Intel for using Intel fabs to produce Mediatek chips so maybe we will see a more consistent supply of chipsets from Mediatek going forward.
New build, last OpenWRT version.
USB radio MT7610U
The Windows PC connects correctly, everything works well.
Smartphone Android connects but without the internet.
DHC from ETH provides correct IP on the phone.
Even setting the phone with static IP/gateway/DNS, it does not reach the Internet.