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DHCP Issue with Range Extender and Multiple Connected Devices

Last response: in Networking
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June 15, 2014 8:44:52 AM

I have a cable modem that has a wireless capability (the primary wireless in the description below), but it doesn't reach the entire house. I have an Amped wireless range extender.

The problem arises when two or more devices connect to the range extender. The first device connects and requests an IP address, which is supplied by the DHCP server associated with the primary wireless. This DHCP server now has the granted IP address (call it 192.168.0.10) associated with the range extender's IP address.

Now a second device connects to the range extender. It, too, requests an IP address. The DHCP server grants the IP address (call it 192.168.0.11) AND ASSOCIATES IT WITH THE RANGE EXTENDER's IP address. The DHCP server no longer has any record of 192.168.0.10.

At this point, one of two problems can arise:

The device using 192.168.0.10 requests a renewal of its IP address lease. The renewal is denied because the DHCP server no longer has any record of this IP address. The device eventually completely disconnects and acquires a new IP address. Unfortunately, any network activity (e.g. large file download or streaming video) is completely disrupted at this point.
Some other device requests an IP address from the DHCP server. Since the server now has no record that 192.168.0.10 is in use, it issues this IP address, which now causes an IP address conflict.

I would appreciate any guidance you can give me on how to resolve this.

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a c 122 F Wireless
June 15, 2014 11:12:01 AM

Sounds like the amped device is not working properly. I stopped using them years ago when I found they intentionally were misleading in their advertising about how much power their equipment puts out.

The only way a repeater works properly is for it to pass the actual mac addresses of the end stations to the router. This is done via WDS. Since WDS is not standard it does not work on some routers. To fix this some vendors do their own thing and attempt to do mac NAT functions. This has limited success and is why it is not common. You would have to run in full routed nat mode if you can not get WDS to work. This would mean the repeater would be giving out the IP.

WDS is required to get any kind of wireless bridge/repeater to work that has multiple devices behind it. Since the mac address is used as part of the encyrption keys to the main router it can not have multiple mac addresses. To solve this they send the actual mac of the real clients in a field called WDS. This has never been officially standardized so it mostly works but there are no guarantees.

You need to set both your router and the repeater to use WDS if you want to have any chance.
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