Arris SB6183 Modem Status- Questions

So lately (approx. last couple of months) I've been seeing instances of devices, whether it's an iPad, iPhone, or computer, take 30 seconds (or more) to display a web page. Speed tests indicate everything's OK, but I can't help but feel something's amiss here. While I suspect the issue lies with the current firmware in my Netgear Orbi RBK50 mesh router (router plus one satellite), I'd like to try to nail down exactly what's wrong before I start replacing either the modem or router system.

So I ran a modem diagnostic page, and am not sure that what I'm seeing is OK or not. Below is what I see in this diagnostic, and I have the following questions:

1. Are the power levels and SNR values acceptable?
2. Should I be concerned about the high number of uncorrectables on some of the downstream channels?
3. Shouldn't there be more than one upstream channel? Only one is listed in the diagnostic page.

I'm hoping some of you that really understand these things can help.