Not sure why Comcast would feel the need to charge for a service call. Since they are responsible for signal to your modem. Whether you own it or they do. I own mine.
Main thing to remember is no splitters in between the cable and the modem. If a splitter has to be used it needs to be one that is bidirectional, 1 Ghz minimum frequency, and unequal power (dB) division. More commonly known as a cable modem splitter.
Kind of easy to identify. You will see the In port and two Out ports. One port out will show something like 2.5 dB and the other showing 3.5. I don't have one to verify the numbers right now. The lower dB port will go to the modem obviously because it will have less signal attenuation.
The first thing most any field tech will do is cut and splice in new connectors. Their field equipment would be able to test signal and dB of each u/d channel. For your cable pedestal to have ants and anthills in it is not uncommon.
As long as the cable jacket is good, you're good. Ants are nasty and love electricity for some reason.
If Comcast techs aren't willing to dig the crud out then you should and wipe the cable clean. Look for damage.
Or try dousing it with the hose and see if your signal goes south. Right?
One thing to look for also is in the modem management screen. After a reset. Look for uncorrectables that increment in huge amounts on one or more channels after a screen refresh (F5 or the reload icon).
If you see some channels steady and one or more incrementing in huge numbers. It could be the CMTS at the headend is flaky. I learned that from my higher lever cable engineer.
Mine would go 224, 700, 998, 1500, 1900, 2450, 2470, 3500. Just an example of course. Every time I refreshed my screen as often as I could. The tech saw it looking at the modem stats at the headend. Swapped a CMTS card in a rack and it was fixed. All day long and maybe 50 uncorrectables. Sorta'. Not 100% full of bs, but it's a good description
Crappy cable or coax connection will increment uncorrectables across all channels. Could be a bad line amplifier.
Could be a poor connection on an F connector. A bit tighter than finger tight will do.
But why they would charge for a service call is plain nuts. Even if you do have 47 splitters. Its their job to find and provide a fix.
All of the errors are covered in web searches like this one:
We are no strangers to the occasional network disconnection in the middle of a work call or a high ping on a Warzone server.
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