Hi Miguel,
The “general” EIGRP troubleshooting lessons can also be applied to DMVPN, the only thing you need to keep in mind are the differences with the DMVPN phases.
Have you seen my EIGRP examples for the different phases?
Here’s what you need to keep in mind:
- When using phase 1, all traffic goes through the hub so the next hop address doesn't matter. Just make sure that the spoke routers have a (summary) route. If you don't use summarization then you need to disable split horizon on the hub so the spoke routers can learn each other's networks.
- When using phase 2, there is direct spoke-to-spoke traffic so spoke routers a) need to know each others networks and b) the next hop has to be correct. This means you have to disable split horizon and disable ip next hop self on the hub.
- When using phase 3, the spoke routers require "something" in the routing table to reach each other. It doesn't matter what the next hop is since NHRP will overwrite it. If you don't use summarization then you should disable split horizon on the hub.
Hope this helps!
Rene