I do some research and 2-factor authentication has nothing to do with WebDAV authentication. WebDAV authenticates only by user id and password.
I also did some test with our Synology NAS and even if I activated the 2-factor authentication there is no problem when mounting WebDAV from NetDrive using only user id and password.
Can you send us a debug log file if you cannot connect to WebDAV using a user account with 2-factor authentication?
After setting the log level to VERBOSE, please reproduce the problem and send us the debug log file :
There is no credential information in the log files.
Sorry for the inconvenience it may caused.