I just added a starlink Gen 3 router to an available WAN port on a balance two (Well a virtual WAN).
All is working well,however, the starlinkGen 3 router is creating a DHCP range in the 192.168.1.x subnet. That is the range on my local LAN. (192.168.0.x 255.255.252.0)
Starlink does not allow to change the DHCP range. The only option is bypass mode, however, I’d rather leave the Starlink device to broadcast a wifi signal “if all else fails”.
Is it a problem to have the same subnet on the WAN side as the LAN? I’ve always used separate ranges, but just curious for opinions from people much smarter than me!
Hmm, I’m not sure I follow. It is ok, but it shouldn’t be done? SOrry. Appreciate if you can clarify as I’m not sure I understand. With the IPs being on the same subnit, it’s kinda hard to avoid duplicates…
I just learned something from @MartinLangmaid’s post. I always thought you could not have the WAN and LAN subnets overlap in a router. Martin says just make sure the IP’s do not overlap.
So apparently if you set up your local LAN DHCP address range and any static LAN addresses to be above 192.168.1.255, you will never experience a WAN IP address from Starlink that overlaps with LAN addresses, and you will be good.
Example time.
Lets say I have a Peplink with its LAN set to 192.168.1.1 /24
Its DHCP will typically start at 192.168.1.10 and end at 192.168.1.254.
So a device on the Peplink LAN might get the 192.168.1.10 IP via DHCP and then 192.168.1.1 will be its default gateway.
Traditionally since the Peplink is a router, and routers route between different networks, the WAN would need to be in a different subnet to the LAN.
But Peplink devices are not traditional when it comes to routing over the WAN. We have outbound policy that manages that for us instead, and the context of each WAN and LAN connection is very specifically defined.
So if WAN 1 and WAN 2 of the Peplink are connected to different starlink routers and both give our WAN interfaces an IP of 192.168.1.10 /24 then that’s OK (so long as both WANs are in the default NAT mode).
Where things can go wrong however is if your LAN IP is the same as any of your WAN IPs. Technically the Peplink router will cope and route traffic, but whenever I have had to do this there has always been some weirdness that made me change the LAN IP of the Peplink (ie to 192.168.1.254).
The LAN IP (gateway address) cannot overlap the WAN address, in this case 192.168.1.0 through 192.168.1.255, so anything in the LAN subnet must be 192.168.2.0 and higher. The LAN subnet includes the LAN IP (gateway), the DHCP range, and any devices with static addresses. Note: If the Starlink DHCP range is less than 255, then you can also use anything in 192.168.1.x that is above the end of the Starlink DHCP range.
Reading between the lines, Peplink in “default NAT mode” perhaps manages the NAT assignments from one port pool across two WAN’s with the same WAN IP address so there is no conflict?
Hosts in that LAN assuming /24 subnet would be .1 to .254.
It is best practice to have different subnet on WAN and LAN but this is not always possible (think hotel wifi as wan).
Not sure what you are trying to say here.
Yes kind of. Because the WANs are designated as such in code, the peplink treats their use differently to LAN subnets for generic routing as typically outbound policy is used for WAN routing decisions.
I was trying to say that if the Starlink router allows you to configure the DHCP range, as most routers do, that if it is configured to say 10 through 200, then above 192.168.1.200 is available. Unless of course some other devices connected to the Starlink router are configured with static IP addresses above 200.