Results - 2.4GHz Bridge
On 2.4 GHz, we were working with roughly 42 Mbps downlink and 56 Mbps uplink throughput available for the extender to pass along. Note that those are throughput numbers measured using the test laptop at the extender location.
I also tested performance at the Ethernet port for all but the D-Link, which does not have an Ethernet port. So let's see how the devices ranked just transmitting back to the router first. This essentially uses them as wireless bridges.
2.4 GHz downlink performance at Ethernet portWe can see that on downlink, most of the extenders had ballpark closeness to the throughput back to the router as my laptop did. Also take note of how similar most are. The TRENDnet TEW-737HRE however yielded higher downlink throughput than the reference laptop. I repeated the tests multiple times and the TRENDnet's higher throughput was consistent. The board photos from the FCC ID docs show it uses two Microchip (SST) SST12LP15B power amplifiers. It's not the only extender in the roundup to have external amplifiers, however. The D-Link DAP-1320 and Linksys RE1000 do, too.
TRENDnet TEW-737HRE board
For uplink, the extenders also had slightly less than the 56 Mbps I saw with my laptop. Most of the products were clustered closely together, with few significant differences. The TEW-737HRE is once again out front.
2.4 GHz uplink performance at Ethernet port
Results - 2.4GHz Extender
We would expect best case extender throughput to be about half of the baseline values and that's roughly what we saw. There were a few surprises that were over 50% of their wired / bridge throughput, however. The image below shows the charts comparison of 2.4 GHz downlink for the N300 models.
2.4GHz downlink performance
Note the almost 3-to-1 difference between the maximum and minumum results for downlink. Note also that products change position between uplink and downlink.
2.4 GHz uplink performance
Aside from the unusually high TEW-737HRE downlink throughput, the results are so similar you would be hard-pressed to detect a difference in real-world use.
Results - 5GHz
In our N300 group, the only extender able to operate in the 5 GHz band is the Linksys RE2000. When used as a bridge to its Ethernet port, it produced 50 Mbps downlink and 62 Mbps uplink. 5 GHz reference measurements made with the test laptop were 72 and 79 Mbps for down and uplink, respectively.
When used as a wireless extender, the RE2000 provided 36 Mbps downlink, but only 13 Mbps uplink.
I will reiterate that the RE2000 can't extend both bands at the same time. Despite its unique features, the RE2000 seems like more of a niche product. If you were looking just for 2.4 GHz, you'd buy one of the better-performing and cheaper extenders such as the TRENDnet or TP-LINK. If 5 GHz extension is what you are after, you probably want simultaneous dual-band.
I also had the same problem with the RE2000 that Tim had back when he first reviewed the RE1000; it just went away and it took me quite awhile to figure out how to get it back again. I'd advise against the RE2000 if you are looking for a dual-band extender. And lastly, the RE1000 somehow managed to crash my router 3 times. I'm still not sure what happened there.
Looking at the Wireless Extender Ranker, we find the same top three products as our first go at this found, but with new positions. The TRENDnet TEW-737HRE has moved up from third to first place, with the former first-place TP-LINK TL-WA850RE right below it. The NETGEAR WN3000RP moves one place down from second to third.
Ranking incorporates both down and uplink throughput and also factors in wired throughput. But wired throughput carries only 25% of the weight of wireless throughput in the total ranking, so it's not a major factor in total score. After all, most people don't buy wireless extenders to use as bridges.
N300 Ranker Results
Here is the performance summary detail for the top-ranked TRENDnet. Check the Wireless Extender Ranker for details on the other products' performance.
TRENDnet TEW-737HRE Ranker Performance Summary
With the higher throughput that N class routers provide, wireless extenders can provide enough throughput for web browsing, email and other low-bandwidth activities in previously unusable dead spots. And with today's super-efficient video codecs, they might even provide enough throughput for casual YouTube viewing. An extender might also be cheaper than a pair of powerline adapters. But they still don't beat adding an access point connected preferably via Ethernet, or MoCA / powerline if Ethernet isn't possible.
If you decide to try one, there are a few caveats to keep in mind. Wireless extender performance can very greatly, especially when used in environments with lots of busy neighboring networks. I think it's safe to say that if you have trouble holding a wireless connection with a strong to medium signal connected to your current router, you'll have as much or more trouble with a wireless extender.
Extender reliability is another weakness. I did not run long-term testing on any of the extenders, so I can't speak to extender connection reliability. But when I've used extenders in the past, they have tended to disappear from the network after a day or so and need rebooting. That may still be the case; your mileage may vary.
The bottom line is that if you have a wireless dead spot (and I do mean dead) and need to light it up for basic internet access, any of these products can do the job. Just don't expect throughput miracles and be prepared to deal with disconnects, especially if you have a lot of neighboring networks.