debian server fault finding

Hi All,
The debian server that I built a few years ago thanks to the help I received from this site, may now be running a little bit suspect. I am trying to narrow the fault down to (A). Server problem, (B). Internet problem or (C), other issue.
Problem is that some channels will 'glitch' for a short while and then run fine for say 2 or 3 minutes. The ecm's all seem to be in the .200 to .3130 region. I have 2 X smargo's installed and have tried the server with one smargo at a time and compared results. Removing one smargo appears to make no difference to the problem.
What is the best way to check out the internet connection to the server. Is using VE network catcher the right approach for checking the internet service or should I be looking at log's etc to help find my problem.
Any advise is appreciated.
Thanks in advance.

Thanks for your response.
I may have confused you on the ecm figurers. They vary between .200 and .313's. I am running CCCam 213. The problem seems intermittent. It's fine today with the same ecm times. What should I look for in the logs. I never looked at them before but am willing to learn.