Hi jamesb33, I just wanted to summarize what all has been suggested here.
As alemabrahao mentioned, there is no need to create a new Dashboard Network and all of your Meraki gear will check back into Dashboard and continue operating as expected once the gear has an internet connection again. Be sure to change network-specific items such as the devices' placements on the map or floor-plan if you are leveraging this functionality (https://documentation.meraki.com/General_Administration/Monitoring_and_Reporting/Placing_Devices_on_...).
For your new building's internet connection, be sure to have all of the static IP specifics from your ISP (static IP, subnet mask, gateway, etc.) so that you are able to get your MX back online without any problems.
We most commonly see customer's leverage the "Local Status Page" of the MX in order to configure the static IP addressing on the WAN/"Internet" connection of the MX, which requires that you connect a computer directly to one of the LAN ports of your MX once you have connected at your new building. alemabrahao linked you to the correct resource for this process but I will re-post it here: https://documentation.meraki.com/MX/Other_Topics/Static_IP_Assignment#Local_IP_Assignment . You could always test accessing the MX's Local Status Page before your move to ease any concerns around this process that you may have.
Alternatively, as rbnielsen mentioned, you could pre-configure the MX's WAN 2 with your new building's static IP specifics but we still recommend having the "Local Status Page" knowledge in the event that there is an error with this pre-configuration or if further investigation is needed once you arrive at your new building.
Hope that helps, jamesb33! For more immediate assistance, be sure to call into our 24/7 Enterprise Support hotline. You can see these options by navigating to Help > Get help from the upper-right hand corner of your Meraki Dashboard portal. Good luck with the move!
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