[smf007]

There were some issues in the past with Samba 4 where people had to put

Code:

min protocol = NT1

In light of the current events I came across this post which seems to actually work. Setting min protocol to SMB2 or SMB3 would result in my Ubuntu 16.04 box not connecting. Also wouldn't work when setting max protocol to the same as the min. But setting protocol explicitly to either SMB2 or SMB3 works!