We have a HP Color LaserJet in the office, one of these which can do both printing and scanning. The newer versions include a very nice feature "Scan to network folder" - so I did setup options to scan different PDF sizes to all of our laptops. Very convenient!
Until it stopped working a while ago.
The printer refuses scans to a network folder with the error message: "Scan Error" "Unable to connect to the network. Check the network, and then try again."
Looking at the printer, it auto-installed a new firmware in April (CLRWTRXXXN002.2014A.00 - Built date: 2020-04-02). Dunno if that is related, but around the same time the scan function stopped working. Haven't really found time to investigate, until now. For the couple cases I had to scan something, I used an USB stick.
First things first, I turned up the logging in Samba - all laptops here run Linux, and no Windows. This - and a tcpdump - did not reveal any new details, but showed that the printer does connect to the laptop, is authenticated as guest user, and then ... does nothing. The error message "Unable to connect to the network" is a lie. Shame on you, HP!
Then I tried to limit the SMP protocol versions on the laptop:
client min protocol = SMB2 client max protocol = SMB3
Didn't change a thing.
Last but not least, I changed the protocol versions on the printer:
- Advanced Settings
- Disable SMB v3
After clicking "Apply", the scanner was suddenly able to scan again to network folders!
It's hard to implement protocols properls ...