Is my splitter responsible for intermittent internet access?

Hey folks,

I’ve been having intermittent trouble on/off with my internet for months now, but even after several visits, the cable company claims to find nothing amiss, so I need a second opinion. I’m pretty proficient at internet troubleshooting, but have limited experience with this specific issue.

The symptoms are as follows:
Random, intermittent lack of internet connection—in network connections, and on all browsers/messengers/etc. When this occurs, the power and status buttons on my modem remain properly colored and steady. However, the incoming, outgoing, and online lights blink (the pattern varies, sometimes it’s one light, sometimes, another…), or go out entirely for awhile. The problem randomly resorts itself after a few minutes, hours, or a day or so, but it always returns and often quickly. It is unpredictable and doesn’t seem to follow a pattern.

I have tried:
– Standard reset both with and without the coax.
– Omitting router altogether. This also omitted any concerns about network frequencies/router channels.
– The modem has been tested and works perfectly.
– New ethernet cord.
– New coaxial.
– All connections are properly screwed in.
– The network is indeed password-protected and encrypted.
– The computer itself’s network driver can’t be responsible, seeing as the actual lights on the modem blink or go out.

So what now? I’d assume that the only issues possible are:
1. The metal splitter (SVI brand, Model #SV-2G, 5–1000mH) that divides the home’s cable port for two uses: TV and internet.

2. Interference between splitter/computer/electronic devices. The computer and TV are about 5’ apart, since there’s only one cable port in the home. However, the same exact set-up worked previously for years.

3. Some outdoor-line problem the company’s missing.

4. ???

Desperate for help or ideas, many thanks-