This is the current situation:
- Subnet 1: 192.168.1.x (255.255.255.0) with default gateway on 192.168.1.1
- Subnet 2: 192.168.90.x (255.255.255.0) without any gateway (no internet access) -> all devices use static IP addresses
I would like to combine these two subnets. I already tried to change the subnet of the default gateway to 255.255.128.0 and it actually worked but I ran into internet connection issues even though everything in the LAN worked fine. My guess here is that my gateway isn't capable of handling that many subnets. So I changed it back to the situation above.
Is there any other way to combine these two subnets? I sadly can't change the IP addresses of the two subnets.
Best Answer
You have a few obvious choices.
Choice 1: Add a link (VLAN trunk or separate physical interface) to your router with an address in the 192.168.90.0/24 subnet. Config your router's address on that interface to be 192.168.90.1, and assign that as the gateway to your clients in 192.168.90.0/24.
Choice 2: Change the subnet mask of your 192.168.1.0/24 subnet to 255.255.128.0 (/17). This will need to be changed on absolutely everything on the network; Router, static routes, firewall rules, clients, etc etc. The reason it didn't work for you before is because some of the devices weren't changed.
It will only be a single subnet at that point. There's no reason a router wouldn't be able to handle a defined /17, unless it's some consumer-grade home router with restrictions to predefined blocks.