Once these has generated some questions among the community, I decided to come up with some information also here at TBs .
Similarly to what happened with BT dongles for NXT, there is a very limited choice regarding working WiFi dongles for EV3.
Until someone changes something in the firmware/VM executable there is only one WiFi dongle that will work with the EV3. It is the NetGear WNA1100 (with USB ID 0846:9030).
You can find these dongles at the moment at several sources, and eventually at your local retailer too.
- Pixmania.com (look at the respective website serving your country)
- LEGO Education (which charges a premium price for reselling this...)
It has to use a specific Atheros chipset (one supported by the ath9k_htc linux drivers, which limits us to around 20 or fewer devices) and then the VM executable checks for a specific USB device ID (unique to the NetGear dongle) before loading the atheros drivers so no other atheros-based dongle works either.
Dongles that use Ralink or Realtek chipsets do not even have driver support in the standard firmware image.
Be aware, before you get to buy something else!...
PS: I've gathered this information from an MCP expert with such firmware topics.