Thanks for all of the advice. I actually changed the router address and the subnet range in one go. After the change a simple dhcp refresh got the wired machines back up, but there was something wrong with the wireless machines. They seemed to have the new addresses, but they couldn't talk to the the internet. So I rebooted the modem, and after that all was well.
I don't expect any particular trouble using this subnet on my local machine. I know it is not going to conflict with anything, since it is reserved to my company, and allocated specifically for employees local DHCP servers.
So, all is well, and thanks again.
It may not have been relevant to the OP in this case, but would it have been possible to use a second router to create a LAN with a separate subnet, then just create routes/NATs to have it play nice with the FIOS router, thus avoiding having to mess with any of the OEM settings?
Yes ... that was essentially the suggestion that I made in my first post. Use a second router in NAT mode with the local segment addressed as whatever range the employer wanted. If you have a NAT router which can be configured in plain "router" mode without the NAT, you could also add a second segment -- the problem here however is that the ActionTEC doesn't always properly perform the NAT translation toward the internet on the second range (plus you have to add the static routes for the other segment, which while not difficult, can be confusing for some).
Installing it as a NAT router behind the ActionTEC would result in a double NAT scenario, but that's usually an issue for almost any scenario except those requiring UPnP features.
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