Not a router issue-- router (Netgear N750) is not blocking any ports, apps, or devices. Parental controls are off. Issue exists on all connected devices (phone-wifi, laptop-wifi, xbox-wired) in the same form.
Started this morning with no internet at all. Reset router, didn't work. Reset router and ONT, didn't work. Contacted Verizon, they reset the connection, and www.google.com started working. Accepted the solution, then switched to wifi connection on phone and suddenly couldn't interact with the verizon website.
Xbox can't connect to Xbox Live (though it claims it can connect to the internet). Computer and phone can always connect to Wikipedia, can sometimes connect to Google, and receive a connection time-out error on the verizon website among a host of others (including all internet speed test sites that I tried).
Verizon won't believe me because I don't have a Verizon router, and they can't confirm that the router is working, so they don't even seem to be trying to check the network.
I noticed that a similar problem happened in 2015 and posted in that thread as well. Opening this one so that a thread without a solution exists.