This looks like an upstream noise (ingress) issue, the FEC alerts in the log give it away. Hmm... be right back...
It's the 24.2 MHz that is generating those errors in the log, on of the 4 upstream channels.
The uncorrecteds are only a few in a billion and were generated when your modem had booted up, not recently. There's nothing wrong with the downstream.
To resolve this, need to first start looking or ingress leaks at the local premise, the modem, the outlet, behind the outlet, at the splitter(s), at the groundblock and at the tap. Try to see if you can spot what your can yourself, and if you find any bad-quality fittings then I would recommend a field technician to assist with that part. What ever would be remaining would be a maintenance issue (fiber optic node 1136 on Kaneohe).
Note this is not assuming any additional LAN (which we are not responsible for) issues which may or may not be present; I'm talking specifically cable plant physical layer. And yes, there does seem to be a phyiscal layer issue on the low frequencies which are used for upstream... hence why your internet is being affected (because your upload frames are being corrupted, which impacts the 2-way communication internet requires).
You have a loose /corroded connection and it's allowing Verizon cellular 4G ingress intermittently. This may be out at the pole. Do you have verizon cellular and how many bars on 4G?
Are you internet only with the modem directly connected to the outside grounding block with no splitters or amplifiers? do the outside connectors look shiny and are all connectors a tad more than finger tight?