If you have an SSH client on a Mac or Linux platform, you can use the -v flag to see the negotiated protocol when connecting to a server (your controller):
MacBook:~ $ ssh -v 192.168.31.2
OpenSSH_7.9p1, LibreSSL 2.7.3
debug1: Reading configuration data /Users/me/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to 192.168.31.2 [192.168.31.2] port 22.
debug1: Connection established.
debug1: Local version string SSH-2.0-OpenSSH_7.9
debug1: Remote protocol version 2.0, remote software version OpenSSH
debug1: match: OpenSSH pat OpenSSH* compat 0x04000000
debug1: Authenticating to 192.168.31.2:22 as 'me'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
....
SSH v1/v2 both use tcp port 22, so you can't tell from there.
If you can find an ssh client old enough, you should be able to use the -1 flag and see if you can connect. I could not find a client that still has sshv1:
ssh -v -1 192.168.31.2
SSH protocol v.1 is no longer supported