Tunnel Gre problem between two hosts (vps and dedicated server)

Hello guys i need to resolve this problem (all server have installed centos 7): i'm trying to create a gre tunnel through vps (in Italy - OpenVZ) and a dedicated server (in Germany), but they do not communicate internally (ping and ssh command tests). Next i create a gre tunnel trought vps (in Italy - OpenVZ) and vps (in France - KVM OpenStack) and their communicate, i next i had create a tunnel trought vps (in France - KVM OpenStack) and a dedicated server (in Germany) their communicate. I can not understand why the vps (in Italy - OpenVZ) and the dedicated server (in Germany) do not communicate, ideas on how I can fix (I also tried with iptables disabled, firewalld is not enable)? Thanks

1. VPS command for tunnel:
   echo 'net.ipv4.ip_forward=1' >> /etc/sysctl.conf
   iptunnel add gre1 mode gre local VPS_IP remote DEDICATED_SERVER_IP ttl 255
   ip addr add 192.168.168.1/30 dev gre1 ip link set gre1 up

2. Dedicated server command for tunnel:
   iptunnel add gre1 mode gre local DEDICATED_SERVER_IP remote VPS_IP ttl 255
   ip addr add 192.168.168.2/30 dev gre1
   ip link set gre1 up

[root@VPS ~]# ping 192.168.168.2
PING 192.168.168.2 (192.168.168.2) 56(84) bytes of data.
^C
--- 192.168.168.2 ping statistics ---
89 packets transmitted, 0 received, 100% packet loss, time 87999ms

[root@DE ~]# ping 192.168.168.1
PING 192.168.168.1 (192.168.168.1) 56(84) bytes of data.
^C
--- 192.168.168.1 ping statistics ---
92 packets transmitted, 0 received, 100% packet loss, time 91001ms

[root@VPS ~]# lsmod | grep gre
ip_gre 4242 -2
ip_tunnel 4242 -2 sit,ip_gre
gre 4242 -2 ip_gre

[root@DE ~]# lsmod | grep gre
ip_gre 22707 0
ip_tunnel 25163 1 ip_gre
gre 13144 1 ip_gre