Zyxel ex5401-b0 + Wifi Printing works half of the time only.

Hey,

TL:DR Version:

Windows 10(64) Laptop cant reliably print or scan on 2 Printers, everything connected to Wifi network of Zyxel ex5401 plus extra (Zyxel) accespoint.

Prints of 6 pages halt after 3.5 pages mid page to never finish and drop error messages (connection issue)

Scans sometimes work, they start, but most of the time they fail. (no data received error)

Detailed Version:

Hey so i just gave my Grandma a brand new Printer only to realise that the issues she had wasnt the printers fault.

She complained that sometimes her Printer (HP Envy something something) connected in the same wlan as her Laptop stops mid print and gives out an error.

It literally stops after 3 and a half pages mid print and halts.

i did a lot of troubleshooting on the windows laptop including uninstalling all the trash that HP likes to install, reinstall the driver etc. to no avail.

Today i brought her her new Epson EcoTank 2826… or something like that and after printing fine for the first test pages the exact same thing happened again.

My Grandma doesnt really get the dates straight but her house got connected to fiber 2 months ago and she got a new router obviously so it might be that the issue started when she got the new router and accesspoint.

My issue is that everything seems to work fine, Printer was found and installed without issues, Epsons connectivy check tool reports no issues at all and on first sight everything works, i can see how much ink is the tanks i can start a print or a scan, when i reboot the printer it immediately reconnects to the wifi and the computer sees it online again.

But as soon as i try to print a document with a couple pages or try to scan something the connection seems to freak out.

Things i tried:

Rebooting (everything, multiple times)

Uninstalling / Reinstalling Printers

Digging through the Zyxels GUI for clues

Disabling Antivirus

Disabling Firewall (in the router)

So i am really at a loss here, if anyone has an idea i would be very grateful, thanks in Advance