Since the same questions about wireless issues come all the time, with people skipping on some very basic troubleshooting steps, here is a list of things to look for when troubleshooting wireless performance.
First important thing to keep in mind: wireless is a two-way thing. When troubleshooting, both the router AND the client device must be looked at. Even if "it worked before", that does not mean that the client (be it a laptop, mobile device or other) must be overlooked.
The first thing to try is to reboot both devices. Sometimes it's all it takes, especially if the router had been running for weeks, or the computer had gone through a couple of sleep/wake cycles since its last reboot.
If you have wireless AND wired performance issues related to your Internet:
Make sure that the cable between the modem and the router is rated Cat5e, Cat6 or higher. Older cables will not be reliable with this router since it has gigabit ports.
Try powering down your modem for 5-10 minutes, then turn it back on. This is especially important with cablemodems.
If you have only wireless issues:
General tips (applies to both 2.4 GHz and 5 GHz)
Issues specific to 2.4 GHz:
The 2.4 GHz band is VERY crowded. You can get interference from a wide variety of devices:
Due to this, you should set channel width to 20 MHz on that band. A 40 MHz connection would require you to overlap no less than 5 channels. Highly unlikely you will get a reliable 40 MHz connection in any urban area with so many channels overlapping. Yes, it will cut your maximum performance in half, but if you want a STABLE connection on the 2.4 GHz band, there is little you can do about this. Otherwise, the 5 GHz band is your only solution.
Issues specific to 5 GHz:
Asus-specific issues
The RT-N66U went through a lot of up and downs in terms of wireless stability. At the time this guide is being written (September 15th 2013), the latest firmware version (3.0.0.4.374.720) should resolves most of
the connectivity issues. Make sure you do upgrade if you are using an older firmware version, and that you follow the instructions from either this guide or Asus's own changelog. Don't skip on that line that says "revert back to factory default and erase your wireless profile". It's not just meant to make you waste 30 mins of reconfiguring, it's meant to save you fromspending an entire EVENING of troubleshooting, which will often end up in you taking that 30 mins of reconfiguration to resolve the issues.
Final advice: just because "it worked fine with that other router" does not mean that it's the new router's fault. Wireless technology is very complex, and relies on a bunch of manufacturers interoperating together. If you really want a 100% reliable, sure-to-work technology, stick to Ethernet. In my personal opinion, wireless should be considered as an alternative to Ethernet where it's not practical to run cables, not the other way around.
First important thing to keep in mind: wireless is a two-way thing. When troubleshooting, both the router AND the client device must be looked at. Even if "it worked before", that does not mean that the client (be it a laptop, mobile device or other) must be overlooked.
The first thing to try is to reboot both devices. Sometimes it's all it takes, especially if the router had been running for weeks, or the computer had gone through a couple of sleep/wake cycles since its last reboot.
If you have wireless AND wired performance issues related to your Internet:
Make sure that the cable between the modem and the router is rated Cat5e, Cat6 or higher. Older cables will not be reliable with this router since it has gigabit ports.
Try powering down your modem for 5-10 minutes, then turn it back on. This is especially important with cablemodems.
If you have only wireless issues:
General tips (applies to both 2.4 GHz and 5 GHz)
- Make sure your computer's wireless driver is up-to-date. Check with the manufacturer's website, as Windows Update does not always carry the latest version (in fact, it rarely does). I've personally seen old Atheros drivers that would refuse to connect to any modern router, but worked fine with some older routers.
- Use a tool such as InSSIDer (Windows) or Wifi Analyzer (Android) to determine which channel is the least busy, then set your router to that channel. Keep in mind that a 2.4 GHz wifi channel will interfere with both neighbouring channels. So if you set it to channel 3, it can be affected by anything also using channel 2 and 4. If your neighbour is on channel 1, then he will also interfere with channel 2. That's why it's usually best to stick with channel 1, 6 or 11, as anything between these will most likely interfere with two other used channels.
- Try deleting the wireless profile from your device, and reconnecting as if it was a new connection. The device tend to save more technical details than just the SSID and encryption, so sometimes that information can be out of sync with what the router is using.
- If you had just upgraded the router firmware, try resetting your router back to factory defaults, and reconfigure it manually. Do NOT load a backup of your saved settings, as this will make the whole procedure pointless - you will just end up reloading the exact same incorrect settings you want to get rid of.
- Router (and antennas) positionning can be important. Picture an imaginary direct line of sight between the router and the client device, and observe what obstacles it has to go through. Each obstacle can affect the radio signal.
- Going through a wall at a 45 degrees angle will also be worse than at a 90 degrees angle, as it means more surface for the signal to travel through.
- Increasing the output power rarely helps, unless you were also able to increase the output power of your client devices. If you really need better coverage, upgrade your antennas. And actually cranking the output power too high can cause more issues than anything if you reach a point where the signal gets distorted by the emitter.
- A 300 Mbps link does not translate in 300 Mbps speed. That's the link speed itself. After that, you have to take into account the encryption, other devices sharing the same channel, retransmission of lost/corrupted packets, etc... Anything around half the link speed is considered good.
- The link speed can also vary based on power management. It's not unusual for the link speed to drop to a lower value, then rise back up as you are actively transferring data. If evaluating performance, do not look at the link speed alone - do an actual transfer and measure the throughput. Timed file copy or an online speed test with a known good test server are good ways to do so.
- Sometimes, some wireless adapters just won't like your router. That can happen with older laptop wireless interfaces, or some specific vendors. If it's practical, consider possibly using a different wireless adapter (USB-based, for example). A 300 Mbps adapter is fairly inexpensive these days - cheaper than switching to a different router (for example, switching to a Ralink-based router instead of a Broadcom-based one).
Issues specific to 2.4 GHz:
The 2.4 GHz band is VERY crowded. You can get interference from a wide variety of devices:
- Microwave ovens
- Baby monitors
- Old cordless phones
- Bluetooth devices
- All your neighbour's routers
Due to this, you should set channel width to 20 MHz on that band. A 40 MHz connection would require you to overlap no less than 5 channels. Highly unlikely you will get a reliable 40 MHz connection in any urban area with so many channels overlapping. Yes, it will cut your maximum performance in half, but if you want a STABLE connection on the 2.4 GHz band, there is little you can do about this. Otherwise, the 5 GHz band is your only solution.
Issues specific to 5 GHz:
- Not every device supports the 5 GHz band. Make sure yours does if you cannot see the 5 GHz SSID at all.
- The 5 GHz band has a shorter range due to its higher frequency. It also means you are less likely to have interference from your neighbours since their own 5 GHz won't reach as far either, so it's both a curse and a blessing.
- Common misconception: people expect higher speeds from 5 GHz. That is not the case. The higher number does not mean higher speed, it only means the router is using a different radio frequency. The reason to use the 5 GHz band is not to get more speed, it's to have less interference (which CAN translate in performance improvement over your 2.4 GHz connection, mind you, but not for the reason you might think).
- On a similar note: simultaneous dual-band means that the router can use both bands at the same time. That does not mean that your computer does - it doesn't.
- The 5 GHz band is usually split in low numbered channels, and high numbered channels. Some devices work best with one or the other, so try out channels from both areas to see what works best for you.
- MAC users: some Macs have issues with the 5 GHz band (and sometimes the 2.4 Ghz band too) and Asus routers. The solution usually requires you to connect to your router over SSH or Telnet, and issue the following commands:
Code:nvram set wl0_reg_mode=h nvram set wl1_reg_mode=h nvram commit reboot
Asus-specific issues
The RT-N66U went through a lot of up and downs in terms of wireless stability. At the time this guide is being written (September 15th 2013), the latest firmware version (3.0.0.4.374.720) should resolves most of
the connectivity issues. Make sure you do upgrade if you are using an older firmware version, and that you follow the instructions from either this guide or Asus's own changelog. Don't skip on that line that says "revert back to factory default and erase your wireless profile". It's not just meant to make you waste 30 mins of reconfiguring, it's meant to save you fromspending an entire EVENING of troubleshooting, which will often end up in you taking that 30 mins of reconfiguration to resolve the issues.
Final advice: just because "it worked fine with that other router" does not mean that it's the new router's fault. Wireless technology is very complex, and relies on a bunch of manufacturers interoperating together. If you really want a 100% reliable, sure-to-work technology, stick to Ethernet. In my personal opinion, wireless should be considered as an alternative to Ethernet where it's not practical to run cables, not the other way around.
