I followed this guide to setup a SSH server on my Buffalo router running Tomato https://www.howtogeek.com/68061/setup-ssh-on-your-router-for-secure-web-access-from-anywhere/
That worked fine and I can connect with Putty from both the local machine and a remote one.
However, I'm trying to connect to it with SSH Tunnel on my Android phone as per this tutorial https://www.howtogeek.com/121698/how-to-route-all-your-android-traffic-through-a-secure-tunnel/ it just says "Error cannot connect to the host". I've just seen the comment about exporting the private key as OpenSSH to use with SSHTunnel, so did that but the same error. The tutorial states to use port 22 but I think this is wrong and should be 2222 as that's the remote port set in Tomato as per the first tutorial. SSHTunnel doesn't really give any feedback as to what went wrong.
If I use ConnectBot, I can reach the router on port 2222 but then obviously it can't authenticate and it says "Your host doesn't support password or keyboard-interactive authentication".
How weird, I just tried SSHTunnel again and it's connected now, so I'll see if it keeps working over the next few days :)