The standard interface for adding printers in Gnome 3 is not very extensive. When you need to add a lot of options, better to use the following:
This will start a GUI that mimics the inputs and outputs of CUPS, that you can find on http://localhost:631/
CUPS does not allow for some characters to be entered in the forms, where system-config-printer does.
The command lets you browse and search for your printer, but if you already know the URL, then entering that URL directly is preferred. Consider the following:
The password will be stored unencrypted in a file only readable by root and CUPS, so will be safe.
You can find this file here:
After changes to this file, restart CUPS
sudo systemctl restart cups.service
Please do not forget to install the packages smbclient and python3-smbc.