If you need an inexpensive DD-WRT compatible router, TP-Link is probably your best choice. But there are some big differences when you compare the TL-WR840n vs the TL-WR841n.
There is a DD-WRT build for the early v1 TL-WR840n, but it does not work on international versions, or on the current v2 hardware that’s on the market today. So it’s sufficient to say that unless you’re very lucky, you won’t be running DD-WRT on a TL-WR840n. The main problem seems to be that it only has 2 MB of onboard flash memory.
The TL-WR841n, on the other hand, is pretty well supported. There were two versions sold only in China that weren’t compatible, but that’s not a problem in the rest of the world. The hardest part is usually finding the right build but I have some help for that. There’s no need to go into great detail on that here.
If you’re interested in DD-WRT, I have recommended DD-WRT settings for you.
The stock firmware on the TL-WR840n is very basic and sparse. The stock firmware on the TL-WR841n is nothing to write home about either, but it seemed adequate. Still, I recommend always upgrading to DD-WRT when possible because of its capabilities.
The antennas on the TL-WR841n aren’t removable, but they are external. The antennas on the TL-WR840n are internal, which gives a cleaner appearance, but it decreases your range.
Both routers are basic 2.4 GHz 802.11n machines. They both support speeds of up to 300mbps, have four wired 100 mbps ports, and no USB ports or any other extra features. They route basic traffic fine, but you’re looking for a router to provide NAS or shared printer support, keep looking.
The TL-WR841n usually sells for around $25, and the TL-WR840n usually sells for $20. Sometimes you can find one or both of them on sale for about $5 off. The extra features of DD-WRT are easily worth $5 or even $10. When there’s no difference in the price, the decision couldn’t be easier: Get the WR-841n.
If you’re looking for the best inexpensive DD-WRT router, I haven’t found anything that consistently sells cheaper than the TL-WR841n. It’s a capable router that’s been a bestseller for several years now, and I can vouch that it works well, at least under DD-WRT. I’ve been using one for more than two years nearly nonstop and have had zero issues with it. I’m very demanding of my hardware and the TL-WR841n always delivers. The version on the market now has a slightly faster CPU in it than mine has, so if anything, it should be a little bit better.
The TL-840n, on the other hand, is a bland, minimal router that only meets the needs of the very least demanding user. TP-Link has a few products like this, and they’ve left a bad taste in many people’s mouths. People who like TP-Link probably haven’t used their products like the TL-840n; people who don’t like TP-Link probably have only used their products like the TL-840n.
If you want something cheap and better than a Belkin or D-Link, get a TL-WR841n. If you want something worse than a Belkin or D-Link, get a TL-WR840n. I probably don’t need to say any more than that. If you’re willing to go a little higher end, here’s what I look for in a router these days.