We’ve all been there. You install a new Ubuntu release and sh*t doesn’t work. It’s really frustrating when it is sh*t that has worked for years. Well, here is how you fix it.
Buffalo (and I suspect some other brands) are horribly behind when it comes to network standards and security. More importantly they never seem to push updates out for these things. I guess that is why they are cheap. What screwed you in Ubuntu 20.04 is a new default minimum standard for network communications. You are going to have to bookmark this fix and refer to it every time you upgrade to a new Ubuntu release until your Buffalo drive dies.
Adding insult to injury, Ubuntu no longer installs the needed packages by default.
When you select samba-common it will automatically select some other packages. Do this using Synaptic package manager, not that other thing you find in the sidebar menu. When you are done it will look like this.
Next you need to open a terminal window and edit a file which didn’t exist until you installed those packages. I always keep Jed installed on Linux machines for just such ocassions.
sudo jed /etc/samba/smb.conf
You want to add the client line where I show it in the file.
client min protocol = NT1
Save the file and reboot. After that you should have no trouble accessing your Buffalo drive.