"Does Ziply offer fixed IP addresses at the lower bandwidth tiers? Perhaps for an extra fee, or a business account?"
A quick Google search seems to suggest that yes, you can get a biz acct. w. a static ip addr and even request to have your personal info unlisted. "As of December 2021, Ziply does not have a "category" that is "residential customer with static IP address". You CAN get Ziply with a static IP address, but you will pay Business rates and be serviced by their Business department. In addition, they will allow you (if you ask) to opt out of business listings so your phone number won't get handed out to companies that make phone calls to businesses. " https://www.reddit.com/r/ZiplyFiber/comments/h8o87o/ziply_fiber_static_ips/
