Many times I will go into a school because a certain classroom is having trouble connecting. Most of the time it is an issue with devices not able to connect on the 2.4 GHz band. I know, use the 5 GHz band instead. Many times the client wants to use the 2.4 GHz, and there is not a lot you can do about it.
The first thing I do is think of the KISS methodology. You know, Keep It Simple Stupid. I pull out my phone and look at the SSIDs broadcasting. If I see a printer SSID, I’ll suggest the customer turn that feature off. The teacher can still use AirPrint as it indirectly prints to that printer without a Wi-Fi card broadcasting.
The thing about HP printers, they were told to use the least busy channel on the 2.4 GHz band. Not, the least busy non-overlapping channel. Channels 3 or 8 seem to be popular choices.
I’ll have the staff disable the Wi-Fi on the printer. Most of the time, it is something similar to this:
Open a browser and enter the IP of the printer
On the Network tab, Click Edit Settings
Under Wi-Fi Direct, change the status to Off then click Apply
Your printer may differ.