SOLVED - SSH simply will not work !!! Losing my mind ...
EDIT: Just scroll to the bottom of the page if this first post here applies to you !!!
We have a Linux Mint XFCE server machine in our livingroom to which we grant access from our upstairs client machine. The upstairs machine is also Linux Mint XFCE. This used to take place via ssh along with an advanced firewall configuration on the server which required the client's IP and the host's password from the client machine, in order to gain access to the server via our preferred (Caja) file manager.
This worked great on Linux Mint 17.2 XFCE as well as 17.3 XFCE after we upgraded.
On August 2nd Mint 18 XFCE was officially released. That same evening I downloaded and installed a clean fresh copy of Mint 18 XFCE on both of the machines that were using SSH previously. This was done onto formatted EXT4 partitions where none of the computer hardware had been changed. Literally everything was the same as before, with exception to the fact that the old Mint 17.3 was wiped out completely, to be replaced with Mint 18 XFCE.
Our connections are hardwired and not wifi. Following the instructions from the link above, I installed SSH Server & Client as required. I had no problem with the firewall settings and I know for a fact that the client's IP in the server's firewall setting is correct. I have double triple quadruple etc etc etc checked everything. Day before yesterday I got so frustrated between trying to set up SSH while also looking at alternatives such as Samba and NFS, that I somehow bricked the server system. So I re-installed Mint 18 XFCE again from scratch on the server machine and started over.
But no matter what I do, I CANNOT GET SSH TO WORK ANY MORE !!!
There are no error messages ever !!! openssh server is installed as required. openssh client is installed as required. Firewall has advanced setting, requiring client's IP for access. Port number rermained unchanged since those are 22 by default. After configuring the firewall, the server machine gets rebooted. Then upstairs, I reboot the client machine for a clean login, followed by opening the file manager and looking for a connection to the server. So far so good, still no errors.
Server Settings: IP number of the server downstairs
Server Port: 22 (by default)
Remote Folder: /
Client Settings: username of the client machine
Password: password of the server machine (have tried both between reboots)
Tick, checkbox for remember password
Bookmark Name: LIVINGROOM
That's where an error comes up ... please check your user information ... with an exclamation mark in the password field.
I know for a fact that the server's password is correct.
I've even tested sudo terminal commands on both machines to make sure all was well.
But it doesn't even matter if I use the server's or the client's password ...
because I receive the same error either way, then permission denied after 4 attempts.
This is driving me up a friggen' wall.
Four days, and I have no idea what I'm doing wrong.
Today I attempted the same thing with two Xubuntu machines ...
I did not use a firewall at all, just to see what would happen ... identical problem !!!