Preventing router attached to LAN port from serving DHCP to other devices on other lan ports of B30

I have a peplink balance 30, firmware 5.4.9 build 1732. Attached to the 4 LAN ports are 3 devices, plus another router. The router is actually in another room of the house, connected by an ethernet over powerline adapter, if that matters.


Two wans <–> Peplink balance 30 <—> Ethernet over powerline ----powerline----Ethernet over powerline <----> Another router

The peplink has IP as gateway. The router “Another router” has as its gateway address.

Occasionally, the 3 devices attached to the balance 30 stop using their assigned 192.168.3.x IP address and suddenly acquire a 192.168.1.x address. I guess this is at time of lease renewal because it happens to all of them at the same time.

This results in loss of internet connectivity.

I solve this problem by disconnecting the powerline adapter from the peplink, then release/renew IP of the other devices. They then go back to 192.168.3.x as usual. If I just release/renew without disconnecting the powerline, they just get another 192.168.1.x address. @_@

Anyone have any idea why that router is serving DHCP to these other devices, and how to stop that?



Hello Jack,
Do you mean your LAN have 2 gateways? Peplink at and your router at If you are not implementing VLANs on your network, there shouldn’t be 2 different broadcast domains.
From how I see here, you should disable DHCP on your router. This way, all of your devices will grab IP from Peplink only.


Hi thanks Florence. The router needs DHCP on because it services a room in the house that is not accessible to the main peplink device. There are several devices in that room that get internet connectivity through that router. 99% of the time, that router just respects its proper place and serves DHCP to devices that are connected to it in that room. What I want to block is it servicing DHCP backwards through the peplink to devices hooked up directly to the peplink. I was wondering if maybe I could block some ports within the peplink from communicating with the device. To prevent traffic to/from the device that would block dhcp from coming from that device through the peplink.

Or do you mean I could disable DHCP on the device, and turn the router into a bridge and the devices could get IP addresses from the peplink? Would that work over wifi through that device?

DHCP works at a lower level than IP addressing - there are no ports to block. Are you saying that room 2 (x.1.1 net), is connected to the peplink as a lan client with a 3.x address? Or has its own gateway to some other internet source, and the dhcp problem is noise that leaks across the common powerline aspect?

Yup the x.1.1 router is a client of the peplink with a .3.x address, correct. There are 2 WAN lines in the house, both going into the peplink. The peplink serves DHCP to a few computers in the same room as the peplink. Then there is a router in a remote room of the house, that is connected to a LAN port on the peplink, using a powerline adapter. Most of the time everything works ok. The router gets a 192.168.3.x address from the peplink, then in turn provides internet connectivity to several devices in the other room.

Just occasionally, for some reason/somehow, the devices in the same room as the peplink suddenly start getting their IP address from the router. I know this is the case because if I release/renew IP addresses, they stay 192.168.1.x. There is no internet connectivity. But if I disconnect the powerline adapter, essentially breaking the connection to the other router, then release & renew, everything gets 192.168.3.x addresses as usual and every device is happy again.

It definitely sounds like your powerline adapter is the source of your problem and the fix is easy.

From what I can tell, you have some devices in that other room that need Ethernet connectivity so you hooked up a new router there for this purpose and technically they don’t need to be on a different subnet. This device should actually be just a dumb switch and not operating as a router.

You just need to reconfigure it by disabling DHCP, assigning a 192.168.3.x address to the the LAN, and then connect the powerline adapter to a LAN port instead of the WAN port. This will also retain wireless connectivity if it is serving up Wi-Fi as well.

This way all devices in your house will receive DHCP from the Peplink.

Great! Thanks I will try that.