GRE tunnel and a ipv4 subnet /29

From: Jack Raats <>
Date: Fri, 11 Mar 2022 22:45:10 UTC
I have an ipv4 test subnet from extraip 37.x.y.0/29

My internet connection has ip-address a.b.c.d.
I've a Fritxbox router and behind NAT is my FreeBSD server with 
On this router I've opened the firewall for GRE to my FreeBSD server.
On my FreeBSD server rc.conf has the following lines:

ifconfig_gre0=“inet 37.x.y.2 37.x.y.1 netmask tunnel 
a.b.c.d gatewayip”
route_tunnel=“37.x.y.0/29 37.x.y.1”

This doesn't work. Whats wrong? Do I forget something?

Jack Raats