If you want to change your IP address without using a VPN in Windows 11/10, edit the IP address settings or use Command Prompt.

If you want to change the IP Address of the Domain Controller on your Windows network, follow the 4-step process described in this post.

Looks like it's not "5 static IP addresses on 5 devices behind DSL modem in Bridge Mode", but 5 addresses behind PPPoE. If so, you need only one PPPoE connection on one of the routers (1), also ...