SSH working from WAN, refused on LAN

This has been driving me nuts for weeks, now. ArchLinux.

On all my local machines (varied between Arch and Raspbian) I can ssh between them all, except my laptop, which refuses connections from the LAN:

Code:kex_exchange_identification: read: Connection reset by peerIf I connect via WAN (I have the necessary ports forwarding set up on the router) I can connect no problem.

• There are no iptables rules
• fail2ban is not installed
• There is no hosts.allow or hosts.deny file

No joy from the Arch forums (though there were efforts), but at this stage, I'm stumped.

I've purged the misbehaving machine of openssh and all configs both in ~/ and /etc, then re-installed for a vanilla set-up with no change.

So, ideas?