When Ziggo change our IPv6 range/subnet, all server already received their new IP address via SLAAC (subnet delegation). Our most important external IPV6 address is our webserver (also needed for LetsEncrypt certificate renewal). When this changes the following updates need to be done on TransIP and our main router/firewall The following steps are required:

1. Get the new IP address that our webserver assigned himself via SLAAC.
2. Update the TransIP AAAA record with the new IP of the webserver
3. On the router update: network/firewall/traffic rules –> Allow-HTTP-ipv6 to new address of webserver
4. On the router update: network/firewall/traffic rules –> Allow-HTTPS-ipv6 to new address of webserver

When Ziggo change our IPv4 address. The following steps are required:

1. Check via external website what our used IPv4 is
2. Check if our router has this already new IP address: Network/Interfaces/WAN/IPv4
3. Update the TransIP A record with the new IP of the webserver