Reverse SSH tunnel failing to open local port on remote host?

I am using the following reverse SSH command to try and open up a reverse SSH tunnel on a CentOS 7 host back to a Debian 10 host.

ssh -p 20000 -NR 20050:localhost:22 user@ipaddress

When I try this command I get the following warning:

Warning: remote port forwarding failed for listen port 20050

It appears the SSH connection is made, but port 20050 is failing to open on the remote host. I am pretty sure that port 20050 is not already open on the remote host. Any help would be appreciated.

Solution 1:

Update: Turns out the authorized key set on the remote host had no-port-forwarding option set. I removed this and now it works fine.