@stephenw10 Thanks so much for all your time and patience, but I finally admitted defeat and gave up. I canceled the Verizon service today and will be returning the gateway device shortly.
I'd love to track down the gremlins and eventually switch away from my horrible DSL provider, but the trial I was on was about to expire, and I was out of time to screw with it for now.
Maybe one day I'll try it again, possibly with T-Mobile home internet, which I think it also in my area. I've heard they will be making it easier to 'bridge' their gateway device soon, so that might be an option.
I really do appreciate all your help, sorry we couldn't come up with a real solution!