Problem of stability

[Aralston]

Hello, I bought this router Asus RT-AC66U to change my old Netgear with Wifi g which crashed nearly everydays.
The router works well just after I start it, I have a good speed (15 mpbs for an ADSL connection) but 1-2 hour later, the speed become more and more slow and the ping increase. I reach 3 mpbs on a speedtest. Sometimes it works good and sometimes not, and I don't really understand why

I tried the following instruction from another post:

1. Update the firmware
2. After the firmware update, reset the router to factory defaults
3. Reconfigure the router from scratch
4. Remove all of your old wireless profiles from computers, phones, etc
5. Make sure 2.4 Ghz and 5 Ghz have unique SSIDs
6. For 2.4 Ghz, change the channel width to "20 Mhz"
7. Change the 2.4 Ghz channel with the help of inSSIDer
8. If you have cascaded your Asus router to another router, make sure it is not double natting on the same subnet. (Change the Asus IP address to something like 192.168.9.1) or use AP mode instead.

And I still have some problems

I post my configuration, if you see something wrong tell me

 

[cmillar6]

You have an open system. To lock in at wireless N speeds you need WPA2. Turn off b/g protection unless you really need it.

 

[jlake]

Possibly your Adsl modem is going bad? How old is it?

Try connecting a PC directly to the modem and observe.

Is the modem in bridged mode? Or is it also acting as a router?

As mentioned in that other thread, you can try moving the asus router to a different location for testing purposes.

 

[Aralston]

The modem is only a bridge, i don't it as router because it is wifi g, and it is from 2008, so maybe a bit too old, i may change it
I can't really move the router because at moment it is at the center of my hause
I turned off "b/g protection" and it is a bit better for the moment