region is Romania,ISP is RDS

Firmware Version:	3.17.0 Build 20150515 Rel.34700n
Hardware Version:	ArcherC8 v1

I have read others online state the Atheros AR965x only supports 2.4GHz at 72.2Mbps, I can't confirm either way since I don't own said wireless adapter and I can't find detailed chipset information on the internet myself.

Are you sure the model number is AR965x?

Atheros was bought out by Qualcomm back in 2011 so if you have an AR card it is likely an old 2.4GHz only card and may be restricted to 72.2Mbps.

Have you tried manually updating the wireless adapters driver?

Windows often automatically installs/uses old wireless drivers when newer wireless drivers are available from the chipset vendor. Atheros never officially released drivers themselves but often driver releases by OEMs for other newer Atheros wireless adapters included updated wireless drivers for other Atheros wireless adapters.

Finding wireless drivers for Atheros devices can be a real pain and that's if newer drivers exist.

https://www.atheros.cz/ has drivers for many Atheros products but not all.