Your physical set up should look something like the picture below if you have a regular modem. Regular modems only have one Ethernet Port and no WiFi built in. If you have one of these skip to Step 1. Otherwise read on.
If you have an all in one modem with multiple Ethernet Ports and Wifi…. You need to turn off the WiFi on such modem and disconnect everything but the OpenWrt Router to the Modem.
After that you just need to enable DMZ or DeMilitarized Zone on the modem so the router can do it’s job. Alternatively for advanced users you can choose to enable Bridge Mode instead if your modem supports it (Please do not do bridge mode if you’re not an advanced user who is familiar with setting a static IP on their computer so they can access the modem).
Comcast Instructions for enabling DMZ: This can be done by plugging a PC into one of the modem Ethernet ports. Then you just need to type in 10.0.0.1 in the browser. After that just login and find a way to enable DMZ on the OpenWrt Router. While you’re at it disable the WiFi for the modem so it doesn’t interfere with the openWrt router’s WiFi. Finally, save your settings and that’s it!
Step 1: Testing your current max internet speeds
For this step please make sure no one else is currently using the internet but you and go to https://www.speedtest.net
Take note of your maximum download speed and maximum upload speed.
In my example below my DL Speed is roughly 55 Mbps or 55000 kbits/s. And my UL speed is roughly 6 Mbps or 6000 kbits/s.
Step 2: Login Router and Adjust SQM
Login into the router by typing in the router’s IP address in your browser. You might need to do this in incognito or private mode of the browser if it doesn’t load. If you don’t know your router’s IP address you can refer to my quick tutorial here. It’s usually 192.168.1.1 in most cases.
Now to adjust SQM please navigate to the Network -> SQM QoS tab.
The Enable this SQM instance checkbox should be checked if it hasn’t already. This thing right here is the reason why you will never lag again. But it requires some adjustments.
Now you need to calculate roughly 85% of your max DL and UL speeds in kbits/s. In my example above 85% of my download speed of 55000 is 46750 so I entered that in the Download speed field.
And in my example my upload speed was 6000 so I entered in 85% of that which is 5100. Then press Save & Apply. If you enter in 100% of your DL and UL speeds SQM will not work!
See screenshot below as an example.
Step 3: Setting Up WiFi
This step is self explanatory. You can just set up your WiFi by going to Network -> Wireless. Then just choose your own WiFi Name (SSID) and WiFi password.
Step 4: Optimizing max speed (Optional)
Congratulations now you have effectively made your Internet at home lag free. Now you may have wondered why 85% of your speed. Well the router needs some overhead (spare bandwidth) in order to perform it’s anti lag properly.
Go ahead and head over to http://www.dslreports.com/speedtest and run the speedtest over there. If you’re buffer-bloat rating is A or A+that means it is working.
Now optionally you can experiment play with the 85% of your speed thing. For example, you could try 90% or your UL / DL in SQM and retest at dslreports.com. If the rating is still A or A+ you can keep it at 90%. Then you could push limits and try it at 92%. If you retest at dslreports and get a B+ or B rating at 92%…. then just go back to 90%. I do not recommend going above 95% of your max speeds.