Bad WiFi? Check the Client

While doing wireless engineering work for a large hospital system, a problem added to my radar. The workstations on wheels (WOWs) were intermittently disconnecting from the wireless network. The client electronic medical records (EMR) application session would disconnect.

The WOWs used an external USB wireless dongle. Specifically the ASUS USB-AC56. This dongle on the manufacture’s website looked quite good. Dual spacial stream 802.11ac wireless USB NIC. The device’s documentation didn’t go into detail which wireless frequencies the dongle would support.

To sell a radio in the USA, each manufacturer has to have the radio approved by the FCC (U.S. Federal Communications Commission). The FCC assigns each device a unique number called the FCC ID. You can look up this FCC ID in the FCC database.

FCC ID Search

The FCC information is often very technical and difficult to read. I determined that the FCC didn’t test the device on the UNII-2 or UNII-2c frequency bands.

The hospital system was using UNII-1, 2, and 3. So could this mean the ASUS USB-AC56 dongle wasn’t able to communicate with 1/3 of the APs in the enterprise? If this is true, then that could explain the intermittent drops and disconnected sessions!






So I did what every wireless engineer would do. I reached out to my buddies on Twitter to see if they had a similar issue. Always use your resources! @Badger_FI is a great guy and always helpful. I trusted his information, but to go to Leadership…I needed some documentation.






Trust but Verify!

So Chris Kent (senior project engineer and all around great guy) deployed up to date drivers and did some initial testing which seemed to prove that the devices didn’t support UNII-2.

To 100% be confident, I built out my lab and did some independent testing. Here is the additional testing to document the ASUS USB-AC56. Plus nothing works better than actual pictures!

Turns out the ASUS USB-AC56 only supports UNII-1, UNII-3, and ISM 165.



So if you have Bad WiFi! Check your Clients!




2 thoughts on “Bad WiFi? Check the Client

  1. Hey

    Very nice read, realy helpful to see the mindset of someone who is experienced.
    I’m trying to get into Wifi aswell and these articles are really great!
    Bookmarking this blog just in case.

    Just some questions on your lab setup (if you don’t mind)
    How many AP’s do you use?
    Which brands/models do you use/recommend?
    How do you have them setup (in one room, 1 in each corner, besides each others, multiple rooms, …)?

    Kind regards


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