Since there is no PC in the receiver those common USB WiFi things never work. If Onkyo does support some USB WiFi stick, they would sell it.
Let's not waste another word about the USB dead end.
1. Some WiFi to Ethernet Client. Some are cheap and easy like the TP-Link TL-WR702N or similar. These are set to client mode and run under 20 bucks here.
2. Powerline networking. This costs a bit more and has more caveats. But it's another solution worth noting.
I have a 5-6 year old Onkyo receiver that is internet capable but didn't come with wireless technology. It's too far from a router to use ethernet cable. I've always thought I could just buy a wireless adapter, plug it in the Onko's USB port and it would connect with my home wireless. However, I finally bought a wireless adapter (Netgear N300) to set up my wife's new Windows 10 machine and it uses an installation disk. Given that, apparently, I couldn't use this adapter with the Onkyo receiver. Is that conclusion correct? Are there wireless adapters that are pure "plug and use" that would work with the Onkyo? I'd like to solve this so I could, at least, do a firmware update on the receiver. Internet radio would be a bonus. Thanks in advance.