PPPoE interface does not accept underscore characters in service name

[filippo1974]

Hi All,
I have a little issue when configuring the WAN interface. In my case, this interface is configured as PPPoE. Important thing: the "service name" field of the PPPoE configuration contains a "_" character. Upon initial creation of the PPPoE interface, everything went fine. But now I wanted to edit this interface and I can't do it because I get a "service name contains invalid characters" error due to the presence of the "_" character in the service name.
I first noticed this issue in opnSense 14.1 and it is apparently still there. Is this a known bug? Is there a way to work around it, other than manually editing the configuration file containing the PPPoE parameters?
Thanks, best regards
Filippo