HappyKayakers wrote:
It's possible they may be using different security protocols. For example, the printer may support WPA while the MiFi is using WPA2.
So long as you're sure you've entered the correct passcode into your HP printer, I also think the likely culprit is an incompatible encryption protocol on the printer end. Are you using WPA or WPA2 TKIP or AES? Not all hardware supports AES router(MiFi) encryption and this can cause it not to connect. My guess is that the Verizon MiFi could be using AES? Try setting it to use only TKIP, and see if it connects?
You may also want to set the MiFi encryption to a less secure settings as a test. Either WPA or WEP to see if the printer now connects? However, I would restore the security settings to the highest most usable level, but not compromise the whole WiFi network for a printer.
Another option is to check if your HP Printer has updated "firmware" available, not just drivers, and see if that corrects the issue.