Yes, I know Cox don't say they block port 8080, but on a fresh factory reset, I can access 192.168.100.1:8080 (but it shows up blank because there's no cable to analyze).
Soon as I plug in the cable jack, though, and it pulls a config from Cox, 192.168.100.1:8080 won't respond and I can't analyze the spectrum which is the whole point of trying to pull up the spectrum analyzer.
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Re: the Zoom Telephonics thing, I prefer the Zoom built ones. I've never had one of them overheat or outright die on me out of nowhere (aside from a literal lightning strike to the coax line in my building). The Arris surfboards, though, drop like flies in my experience. You have to add additional external cooling if you want one of them to last a year.