said by lcs2:
How do I approach Cox about this problem?
There is no way to get a modem to lock onto and stay onto only 1 frequency. The CMTS(What modem talks to) tells the modem what carrier to use depending on different variables.
You need a tech out to find the problem. Cox is almost going to 800mhz + Docsis carriers solely. Here in AZ There are none below 800mhz. Plus when that modem dies and you get a new Docsis 3.0 modem it will need those 800mhz carriers to bond correctly.
If every outlet is your home shows the same low SNR it is wither the splitter at the demarc point, the drop coming in or the plant itself.
Have a tech come out and determine shere the problem is. With the right meter a tech should know rather quickly what is bad and causing the low SNR.