hp color laserjet pro mfp m476dw rejects wifi passphrase & requires removal of network cable

[BTMoose]

I have been on this home wi-fi network for a year now with my HP wirelessly connected over my network.  I have also had a network cable plugged into the back of the printer, although computer does not use the hardwired connection.  A couple of days ago, I noticed that when I wanted to print, my printer would show to be off line.  I would nave to go wake up the printer and then reboot my printer and then I could print.  this happened a few times in as many days.  Today, I did this and it would not work.  So I rebooted, unplugged and reconfigured the wireless on the printer screen Wi-fi setup and it can see the network, but it cannot join the network because when I enter the passphrase (aka password) it says it is "Invalid".  It also would not even let me do this unless I unplugged my network cable stating that the wireless function will not work if it is plugged in.  That is news to me because it has been plugged in the whole time and it worked before.  I have rebooted the router, modem, printer (unplugged) and I am sure I am using the correct network passphrase.    Is there an easy fix for this?  It sounds to me like a network interface issue.

[BTMoose]

Problem mostly solved.  I restored system defaults on the printer and changed the Wi-Fi SSID to "Guest" (instead of my normal wi-fi SSID).  It took my pass-phrase!  Then I signed in on the "Guest" Wi-fi SSID on my computer.   I also cannot get the normal wi-fi SSID to work.  I may try again to use my main SSID in the future, but for now I am tired of the issue and it seems to be working.  We will see if it is a stable connection.  I do not know why the printer previously allowed the cable to be plugged in as it appears that this is a requirement to pick one way or the other to communicate with the printer.