Wrong time zone after area network upgrade

Over the past two days, our neighborhood (Erika Drive, Hopkinton MA) HAS had sporadic internet outages while Xfinity made upgrades to the network (for which we got plenty of advance notice!). Following the completion of the service, the time on many of our internet-connected devices were off by an hour. We traced the issue to our IP address, which our devices use to get the time zone. We fixed the problem by manually defining the time zone on those devices, but is there some way to get our IP address to correspond to our actual address? Perhaps by rebooting the router? There was no problem before the upgrade, so this is not a hardware problem.