davfs and cadaver can't login to server

I try to mount a dav folder and I can't login to it. I got a

Could not authenticate to server: could not handle non-ASCII username in Digest challenge

everytime. After testing multiple time, I assume the issue is with the number, my login is like that : client_XXXX (X replaced by numbers)

When I try to log using "client", "client_" or "client_test" it show this error

Could not authenticate to server: rejected Digest challenge

but with "client_1" "client_0000", etc… , it show

    Could not authenticate to server: could not handle non-ASCII username in Digest challenge

I tried changing the charset of davfs, with iso-8859-1 or iso-8859-15 but nothing change and even if it is related to charset I don't get why it is stuck with simple number.

I precise that I can log in using some client (like web browser or file explorer).

I don't know how to progress here. I'm pretty sure the issue is server-side but of course I can't access and modify it, and since I can log in with some client I assume there is probably a way to get davfs to get in too. Cadaver give me the same error.