Since the last week I have been trying to migrate from C7 to my new C8, but after spending many hours investigate and trying many different steps and HE versions i end up with the same results and problem.
After the C8 reboots and the update tool (:8081) is available and the static DHCP is pingable, 30sec or 1min after the IP stops responding and it just hanged.
The only way to recover the device is to perform a soft reset during this period where the IP and :8081 is acceptable.
The strange this is that i can see the raw zwave & ZigBee devices, so the issue must be related with the app/drivers or something.
Looks like others have also experience this kind of issue.
Static DHCP? Do you mean the DHCP reservation or is the hub on a static ip directly on the hub.
I would for giggles press the network reset button on the bottom of the hub with a paperclip or toothpick for 7 seconds (this is the only round hole out of all the square ones) then make sure you are up to date on your platform and make sure that your c7 is powered down.
Also as a side note, make sure that jumbo frames are not enabled anywhere on your network.
IP dropping will have nothing to do with the ZWave and Zigbee traffic continuing. My first suspect would the DNS Servers - may want to consider manually overriding the entry (Settings|Network Setup|Override DNS Settings).
Try this first. It may make no sense (it doesn't to me). Pressing the button has appeared to make a difference for some users. At best it works and helps point the company in a direction to address this networking issue. At worst you've used up a minute or so chasing the issue.
Something else that just occurred to me. Again, humor me. Remove the dhcp reservation for both hubs from your router and let them grab new ip address' then check their connectivity.