I use VyOS to build DMVPN based VPN solutions and I have noticed a problem.
One of my spoke routers could not join the DMVPN I had setup.
My hub runs 1.2 rolling and the spoke that works runs 1.1.8, the spoke that can’t connect runs 1.2 rolling.
I did extensive troubleshooting but was unable to solve this problem until I finally downgraded the non working spoke to 1.1.8, and now it works.
The problem is not with GRE, since a manual GRE tunnel worked just fine in 1.2 rolling.
The hub router also works just fine with 1.2 rolling so my suspicion is that the problem lies with NHRP on 1.2 rolling but only the client part.
I am not a programmer so this was as far as I could narrow it down.
Hope to help.
With kind regards,
P.S. The spoke router is now in production on 1.1.8 but I am willing to test in a LAB if that will help troubleshoot this.