How to Configure IP QoS for Asus DSL-N12E?

You are likely wasting your time.

First be sure you have the very latest firmware asus has some very advanced QoS options but I am not sure this router can load them.

The huge problem with QoS is that you really can only control traffic you SEND. This only affects the upload rates directly and most people are exceeding their download bandwidth. The download traffic is controlled by the ISP and they don't care. When the connection gets full to your house they will just drop things randomly that do not fit. Not much your router can do its not like it can recreate data discarded by the ISP.

All the DSCP setting and packet markings can only really be used on a corporate network that you control. Even if you were to set the packets the ISP sets it all back to zero...ie best effort. If traffic could be prioritize everyone would of course set theirs to the most important. I have no clue why manufactures put these features on routers that are only connected to the internet.

So the only way to even partially use QoS is you need a router/firmware that can limit to set rates. A number have this ability on upload but again unless you are exceeding the upload rates it does not help a lot. What you want is the ability to limit download rates to a set rate. you would match your neighbors IP/mac and set his download limit to a fixed amount. This would indirectly give your device priority since there always should be unused bandwidth if he is limited. The key problem with this theory is it does not work on all traffic. What you are actually doing is dropping traffic you have already received. So lets say you have a 5m internet and you limit the neighbor to 2m. So the neighbor try to download files ans say the ISP decides to send him 4m/sec. You would then throw away 2m and only give him the remaining 2m. From his viewpoint he is only getting 2m but he is actually still using 4m of your internet connection. What you are depenant on is that the application detect this packet loss and slow down to try to prevent it. Eventually it should only request 2m of traffic because it gets errors above that. It works for many applications but some it does not.

Pretty much you can not use QoS on the internet unless you work with the ISP so they throw away his traffic rather than yours before it gets sent to your house. If you have a large corporate account "maybe" they will do things like that.

So unless you can get other software for your router you are wasting your time....unless you have a very tiny upload rate and are exceeding that.