ISPs have a standard procedure of withdrawing WAN addresses leased to their public network due to IPv4 addresses shortage. This is usually done when the address is put on a timeout or idle.
The WAN address is withdrawn from the network, returned to the ISP pool of addresses, and your edge device is given a new IP address.
When this happens, you will lose access to the dashboard/proxies externally; everything will be working as expected locally, though.
This procedure cannot be controlled from the router or Proxidize server since the ISP controls it. To fix this, you can:
Contact the ISP and request that the WAN IP is reserved as static (This is not always allowed/accepted)
Use Dynamic Domain Name System (DDNS) services: DDNS allows you to create a custom domain linked to your WAN IP address. Whenever the WAN IP changes in the backend, your DDNS will still resolve the configured domain to the currently assigned WAN IP.
Once the domain is configured, you must use it to access the Proxidize dashboard and proxies.
This also applies to using proxies. Connecting to the proxy over port 2001 will require using mydomain.com as the proxy IP and 2001 as the port.
Any DDNS service should work once you configure your router and link your domain to the WAN address. An example of a known DDNS is https://www.noip.com/