Have a situation where we attempted to use the Wi3 Wipnet http://www.wi3inc.com/ MOCA device to provide internet to a media room. Initially I connected it inline with the CATV tuner (CATV feed into Wi3, then out to CATV tuner). The CATV tuner worked fine for a piece, and the Wi3 provided a reliable and fairly speed network access to the room.

However, soon after the CATV tuner started displaying artifacts, or in some cases not even tuning certain channels - sure enough, disconnecting the Wi3 and jacking CATV feed right into the tuner resolved this.

We then tried a splitter (3.5db loss) just before the two devcies; split CATV feed, one side into tuner, other into Wi3. While the latter device worked fine, the tuner continued to display artifacts on HD channels in particular, and again refused to even tune in certain channels; but removing the splitter resolved the issue.

There is already an amp at the main CATV entry to the home; so I'm wondering about the feasibility of dropping in a +8db active amp (e.g., Channel Vision C-0314 [Link: channelvision.com]
or similar just before the two devices? I realize it's best to amplify the CATV signal at the entry point, of course; but since there's already an amp there, I wanted to investigate whether "spot amplification" might work?

Appreciate any thoughts!

And yes, I acknowledge that "Run an ethernet cable" is the ideal way to solve this problem; the location & a couple of other factors make this a 2nd or even 3rd option, behind MOCA or Ethernet over Power.

Since you have a good pic with just the cable box you probably have a clean enough signal to put a low gain amp before the MOCA and catv.

Look up the frequency range over which the internet signal is sent, and be sure the amp you use amplifies that range. That gets internet signal TO you.

Now, what does one do to get the internet signals you're sending back to the internet? I'm not aware of that, but it must be done. One-way internet isn't internet!

I think the appropriate thing to do is to have the cable company replace the amp at the head end of your system with a stronger amp. This will take pulling teeth, as they won't want to do it -- they'll insist that you wire it "properly," as they see it.