SSH Server cannot be found – Even though installed

I have a machine running Ubuntu 18.04 LTS where I cannot seem to get SSH Server working.

I installed SSHServer using:

sudo apt install openssh-server 

but I am getting the following when I try to start and / or check the status:

sudo systemctl start sshd  Failed to start sshd.service: Unit sshd.service not found. 

.

sudo systemctl status sshd  Unit sshd.service could not be found. 

I figured I must have done something wrong (typo?) when I installed, so I tried to install again thus:

sudo apt install openssh-server 

to which I get:

Reading package lists... Done Building dependency tree        Reading state information... Done openssh-server is already the newest version (1:7.6p1-4ubuntu0.3). 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 

So, it appears it is installed, but for some reason Ubuntu cannot find it.

I am not sure where to go from here, so any suggestions would be welcome.

Thanks,

Alan.