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I'm using a TP-Link WR740N router flashed with DD-WRT as a wi-fi repeater. However, in divisions where the signal from the main router is weaker than the signal from the repeater, the Internet speed (as measured with is about a 10 Mbps if directly connected to the repeater, whereas if connected to the main router (with a weaker wi-fi signal) I get about 30 Mpbs. What could be limting the internet speeds, seeing that the signal strength is extended with the repeater?

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Having to repeat immediately halves your bandwidth as everything has to happen twice. – David Schwartz Aug 16 '13 at 23:17
up vote 3 down vote accepted

I believe if DD-WRT is acting as a repeater, it has to switch rapidly between AP and client mode and therefore the speed is reduced. To do AP and client mode at the same time you need two radios in the unit and most hardware DD-WRT runs on only has one.

One workaround is to get a second DD-WRT unit. One needs to be a client on your main wireless network. The second needs to be a DHCP-less/router-less (disable both DHCP and routing in the DD-WRT control panel) AP. The AP can get Internet via a short cable to the first, client router. Try to assign them to different channel bands (i.e. put your main AP and "repeater" client on channel 1 and the "repeater" AP on channel 6 or 11).

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It could be that, as the WR740 is a cheap entry level router, not supposed to work as a repeater. However, DHCP and routing are already disabled as the network main router is the one handling everything - WR740N is only extending the range. Wouldn't acquiring a dedicated range extender be a better solution? – joaocandre Aug 16 '13 at 21:48
It would. But if you have a second DD-WRT-flashable system around it's worth a shot. – LawrenceC Aug 16 '13 at 21:50
One question though: why does DD-WRT reports a connection of 54 Mpbs between repeater and computer? Or is this value measured based on signal strenght alone? Because 54 Mpbs shouldn't cap a 30 Mpbs connection to the internet. – joaocandre Aug 17 '13 at 1:17
I'm looking into this, but the modulation method controls the speed, and the signal strength is what allows a particular modulation method to work. So the speed will align with the signal strength but the radio simply is only going to respond half the time to any mode AP or client, effectively splitting the bandwidth in a time-division fashion between the two modes. – LawrenceC Aug 17 '13 at 18:07
I've also tested using the Ethernet cable. I still get a big reduction in internet bandwidth (~11 Mbps), though not so drastic as with wireless (~7 Mbps). Am I right to assume the issue you stated before is only applicable to wireless connections? So there is something else limiting the speed. Even with the repeater and the laptop right next to the main router I only get about 10 Mbps, vs 80 Mbps directly connected to the main router. – joaocandre Aug 19 '13 at 0:45

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