This is my first question on Network Engineering SE, so I apologize if it is not up to par.
I am trying to help a local business with their network setup, and I have hit a road block. Basically, they have a piece of software that requires a "server" computer to have the IP address
192.168.127.1. Subsequent "client" computers are numbered
192.168.127.2, etc. and all have a subnet mask of
The issue I have come across is that they recently switched Internet providers, and their new gateway/modem is set up as
192.168.2.1. Since each machine on the network has a static IP address on a different subnet than the gateway, they are unable to communicate with the Internet, although they can still communicate with the LAN.
My initial thought was to just change the local-facing interface of the gateway to
192.168.127.1, but that idea was shot down by the requirement of their software, so
192.168.127.1 is already taken.
I then thought perhaps I could change the subnet mask of the gateway to
255.255.128.0, which (I think) would put the gateway and the computers on the same subnet. However, the gateway only allows
255.255.255.224 (or something very close to that last one).
So currently, we are basically stuck in an either/or, where they can either be on the LAN using a static IP address and communicate with their software, or use DHCP and be able to browse the Internet, but without the ability to access the LAN.
The strange thing is, using the static IP addresses some sites still works, such as Google. It appears that IPv6 is still able to work, but not all sites support IPv6 yet, so it is a very limited subset of the Internet.
I have tried manually entering an IPv4 DNS server, but that also has not worked. I am no networking expert, so this may be a very elementary question, but I am hoping that someone here may be able to shed some light on this situation.