[Spirit5676]

Well I'm an IT tech, so those thing didn't look right to me. I assume we need the DHCP for control modules in the car not the laptop/ICOM itself. Laptop/ICOM won't be restarting during the update, so there is no need for them to get new IP's. Modules of the car will be restarting so I assume they need to get new IP's during update.

Would be nice to get a technical document that got some real information on what actually happens during update, so it would be easier to understand the best way to config system. I haven't tried that config, because I don't like to use something that doesn't seem right. I'm not trying to be a smart ass here, I just want to understand what is the best practice to avoid any issues with update.

Actually the gateway setting on ICOM is not required, as the traffic won't leave from the subnet.
All we need are, static IP on ICOM, static IP on computer, a hard or soft dhcpd in the subnet.
When the NBT boot up / restart, it will obtain IP for itself for communication; and the KOMBI with MOST fibre connection to NBT, will treat NBT as their gateway. So if NBT cannot get IP, KOMBI will be update fail too.

That clears it up quite a bit. I was wondering why there was gateway set since the traffic won't leave the subnet as you said. I was also wondering why people were saying to set the DHCP on ICOM and laptop. I prefer static IP's on use like this. So the ROUTER_0 in DHCPSRV.INI isn't needed either. That makes sense to me. Thank you.