router anomoly

[Geoffrey Leach]

I've just replaced a Netgear WNR1000v3 router with an AC1900 R7000. The install went without a hitch, and wireless communication with another system (running Fedora 21) works fine. However, I can't connect with a system running Fedora 19: ssh_exchange_identification: read: Connection reset by peer

The F19 system connects to the internet (through said router) works fine, as does a ping between the two systems. hosts.allow and hosts.deny are both empty.

Any suggestions as to what I've missed?

Thanks.