SSH : launch task and leave it running even if I quit the terminal

Question

I want to launch a task through ssh and then exit my terminal and have my task continuing on my ssh server.

I have tried a bunch of things which did not work, such as :

laptop$ ssh server@ipaddress
server$ mytask &
[1] 12345
server$ logout

Or

laptop$ ssh server@ipaddress
server$ mytask
(then hit [Ctrl]+[Z])
server$ logout

Or even

laptop$ ssh server@ipaddress -f "mytask"
(and then close my terminal)

But even in my last attempt, closing my terminal would stop the task.

How should I proceed?

Thanks in advance!!