I'm trying to set up a gre tunnel between a spoke router with dynamic ip, and a hub router with fixed ip. And it doesn't work.I am using a loopback interface of de hub router as the destination tunnel ip in the spoke router. May be the problem that no use an ip of phisical interface?
IPsec supports dynamic peers, it's all in the documentation.
We also used EzVPN, that works better in presence of NAT.
As mentioned, I have DMVPN without tunnel protection, works fine.