Switch dropping all packets hp 1420 24g

Having an interesting problem with a switch. It's in a new office with a single cat6 cable from main switch in older office. The hp switch was working fine until recently when it refused to send dhcp packets. Systems on the switch could happily talk to each other but not to anything else on the network. If i connect the cable from the old office to any other port on the switch same problem but if I connect directly to my system it is fine. Likewise with a wireless router it works fine if connected directly to the cable from the old office but no if through the new switch. I replaced the switch and seeing the same problemishes with a new HP 1420 24G. Appreciate any guidance anyone might have or even if you have run into something similar? My next step is to get a different model switch and see if that makes a difference!