I have 2 Cisco routers 1811 and I try to configure DMVPN GRE+IPSec tunnel + NAT over Internet between two remote sites for our company, with dynamic EIGRP routing and private traffic over tunnel.
During the last days, I success to get IPSec and GRE tunnel to work but I cannot ping the tunnel IP address from both sides. From the Central router the EIGRP is always up/down and cannot keep a route but the router can send Hello and receive throught the tunnel. From the remote router no up/down, it can send Hello but no Hello received throught the tunnel.
It's a strange problem, I try the classic debug commands. I read the Cisco faqs about mtu issues and tunnel problems... but I cannot fix the problem. Could you help me ? The configurations and debug are attached.