How to monitor quality of internet connection?

Had a big storm this weekend and my Spectrum internet is only sort of working.

Was your Spectrum Internet fine speedwise before the storm?

If it was then the storm might have damaged the NICs on the PFSense box and the TP-Link TL-SG108 switch.

Here only use TP-Link managed switches.

You have validated that the modem still connects fine. And if the PFSense box Gb nics worked before the storm then they could have been damaged. The PFSense Realtek fix was implemented two years ago. Initially it was just an upgrade of the BSD drivers.
Here only use TP-Link managed switches.
Hi Pete,
I only use TP-Link managed switches. They have been surprisingly reliable considering their price point. I started using them when we were having issues configuring Lutron lighting systems with the local ISPs router. When we put the TP-Link managed switch in-line, all the configuration issues went away.
Yes initially here when going to Gb (quit using commercial Cisco switches in the late 1990's) and purchased a tiny TP-Link Easy switch for the Leviton media panel mostly cuz it the telco section of the basement...

So have added one TP-Link Jetstream L2/L3 switch and a few Netgear managed switches to my collection here. I do not see the Jetstream with the TP-Link discovery program.

Had another storm here and Spectrum is behaving poorly. Often get failure to connect to a site but once connected it seems quick. Looked into DNS. I haven't added any DNS servers - just using what I get with DHCP. So I added Didn't have time to do much testing but it seemed to be a big improvement.

BTW, when we had the storm was in the evening. Spectrum went down several hours AFTER the storm had passed. Came back up about 18 hours later. Seems strange on the timing...
For XFinity and PFSense here use two favorite DNS servers and configure DNS Resolver service which is enabled by default.

I just point all of the devices on the network to the PFSense IP for DNS and NTP here.

NTP is an NTP with PPS service running on PFSense with an outdoor antenna. Sees 11 satellites for time sync.

I'll repost the blog that was here and on the PFSense forum for configuring a GPS / PPS connection. It has to be RS-232 and not USB.

Note too that here XFinity doesn't have power backup on their network beyond my house. IE: here modem, PFSense, switches are all on UPS.

Backup up to ISP here is T-Mobile and it does work...a tad slower than XFinity.

Many times I have rebooted the modem and it does come back.
I am just using a combo LTE modem (Combo - Firewall, WAP, Router, Switch with RJ11 port). It also has a battery that goes for a couple of hours and is also plugged in to a UPS. Used to use an Ericsson W25 3G combo modem (many many years).

I just put one of the SIM cards in my Windows 11 tablet. Works great.

Easy to configure failover on PFSense and number of seconds that it takes over.

I am using one of my T-Mobile SIM cards in the LTE Modem. ($25 month).

Found out from XFinity that there is no redundancy (power failover) locally if there is a local power failure (storms et al).

That is not good if you depend on VOIP at home. VOIP does work over the T-Mobile connection which is good.