WiFi Connexion Problem + Smiley lines

[ap1827]

Good afternoon,

I have a Laser printer HP Color Laser MFP 178nwg, bought recently, with a Macbook Pro 11.01 Big Sur. 

I often use the app HP Smart, which always works. I have also tried the HP Scan app, but it didn'rt solve my problems of connexion with wifi.

Here is what happened:

One day, I had problems connecting my printer to my wifi, and I decided to delete my printer from the list in "Settings > Printers and Scanners" and re-connected it to my wifi. Since then, I've had several problems.

First, sometimes, when I ask the printer to print a document, it prints ca. 1 line of smileys and uncoherent typographical signs, like letters, numbers, punctuation signs, symbols (for example "&", hearts, small geometrical forms), on many pages. I have to stop the printing process by clicking on the icon with the red cross, "cancelling". It wastes lots of paper.

Secondly, I have problems with connecting my Wifi with my printer. My wifi connexion is normally good, quick, without problems. I also use it for my cell phone. Until today, everthing worked fine. Now sometimes, the printer works normally, and sometimes, it says that the printer is offline, while it should be online and is on. When it says that it is offline, I can't print anymore. The Wifi connexion with the printer seems unstable: in "Settings > Printers & Scanners", the colour of the printer changes often, from red to yellow to green... On my printer's screen too, I regularly check my wifi signal, and sometimes it says "good", sometimes "weak"...

I tried to identify the problem with the app HP Smart, and it says (see picture enclosed below) that my "current wifi is 5 GHz, while this printer can only be connected to a 2,4 GHz network". This seems strange to me as it has always worked before with my wifi.

Another thing is also that I tried to connect my computer to my printer with a USB cable, as a temporary solution. Sometimes it works, and sometimes it suddenly doesn't work and says "unable to find printer".

All in all, it seems to me that my Wifi connexion might be unstable.

Could someone help me please? Maybe there is a way to reinitialise the connection between wifi and printer?

Many thanks,

Best regards,

AP