I've got a cisco 1921 in a lab setting where we've added an extra interface (EHWIC-1GE-SFP-CU) and as long as a network cable is connected it works fine.
However if the network cable is disconnected and then reconnected the inteface doesn't start up again until I log into the router, enter config mode for the interface and issue
wait for a while and then issue
Doing this makes everything work again, but in a production setting that is, unfortunately, not a viable option. Why does this happen? Is it a hardware fault? Config issue?
interface GigabitEthernet0/0/0 ip address 10.0.4.35 255.255.255.0 no ip redirects duplex half speed 10 no cdp enable !