Although Verizon does not seem to notify anyone (especially clients who are not active on the website or this forum); it seems that some time in 2017, verizon abandoned MyFiosGateway.com (and presumably let the certificate of authentication lapse).
Although the old email inmplies 'no other changes' from the corporate shedding of Verizon's email services (to AOL), this suupport domain is another loss of service for our creeping costs & stock value increase.
When I gave up on a reply here, phone support tech said she could not brows that domain.
What ever function / service that was there, you will have to use some other way to skin that cat.
It turned out neither of us knew about the difference between my router's web & home facing IPs.