I plan to use two RPi3 B+'s communicating with each other. So far I have only one, and am testing its use using a laptop with Ubuntu 14.04. WLAN (via WiFi) works without any real hitches, but I would prefer direct-wired, and have bought a crossover cable to try this. But I cannot get communication, even though pinging in both directions works using the IP addresses. Any ideas?
What are you using SSH for communication and how are you connecting? There are a few jobs that the router does such as assigning names to IP addresses.