Solution Archer C1200 USB Share in Ubuntu 20.04
Just because I didn't found here the right answer I share it with the community if anyone need it.
If you trying to access a shared USB from this device you will unable to do so in newer versions of most Linux distros. This is because the default is to use newer versions of Samba and this device uses V1. So, to solve this, you can mount the share specifing in the /etc/fstab file the version needed, with a line something like this:
//<Network/Media Server Name> or <IP>/<Folder Name> /mnt/<mount directory> cifs credentials=/home/<user>/.archercreds,vers=1.0.iocharset=utf8,sec=ntlm 0 0
Notes: importan thing here is the vers=1.0 option, and I use here an external credential file called .archercreds that contains username=<username> and password=<password> of the authentication credentials in the device, options can be passed as string in the fstab file too.