Some channels unavailable

Hello, I've gone through all of the online and STB troubleshooting procedures for some channels unavailable. I've narrowed it down to likley being the main coaxil cable that runs under the house.  We just had fios installed on June 16th, and have been having this issue since. I've tried a new spliter, still didn't fix the issue, tried multiple coaxils that run from splitter to TV. However, if I take the main line, bypass the splitter and connect straight to the STB it works perfectly. So I'm literally spit balling, but I'm thinking the signal strength in the mainline is weak, thus when running through a splitter it dampens it enough to cause the problem. Our internet also seems to be sluggish. I've tried several coaxil cables to and from splitter/tv and 3 different splitters, all same issue, only fix is bypassing splitter.  I'm assuming this is probably the time to call for a Tech, but I'm not really on par with the Idea of having to pay for a Tech when its been less than a month since installation. I believe the tech used the existing coaxil that was running to where we have our STB, so does this mean if he used the existing line, and the cable itself is the issue, then we are responsible for charges?

Any help would be great, thanks!

Re: Some channels unavailable
Community Leader
Community Leader

Can you describe how cabling is run?

Ie from ONT there is coax of approx length to splitter, then any other runs and splitters.

Also, what type of coax is it (should be printed on cable).

Were splitters provided new from Verizon or existing?