Port Allocations through VPN Connections
If VPN connections are configured and enabled in the FRITZ!Box, then the ports with the numbers 500 and 4500 are allocated. These ports cannot be allocated to other services. If the ports are already allocated to other services, they will be redirected to other ports when a VPN connection is configured.
| Port number | Use |
| 500 | IKE queries are accepted at port 500 by default. |
| 4500 | When IPSec is used behind an NAT firewall, IPSec queries are accepted at port 4500 by default. |
An overview of all of the ports allocated in the FRITZ!Box is presented under "Diagnostics / Security".