Hello there,
having some issues with site to site VPN, IPSec with preshared key.
The setup was working for three years, with almost no issues. At 29.12 suddenly it stopped, the VPN tunnel does not come up at all.
There is one main HQ 750GR3 router, and three routers also 750GR3, which are connecting to HQ.
Routers are not behind NAT.
For Peer Addresses I am using MT Cloud DDNS name on all routers.
The tunnel get established as soon as I use public IP addresses in the IPSec Peer config, but it is not working with MT Cloud name anymore.
Tried restarting all MT routers and ISP modems, NTP time zone and clock are in sync over all routers. Tried changing DNS servers in MT routers, tried with 8.8.8.8, 4.4.4.4, default ISP DNS servers and so on.
I am able to ping all MT routers by its Cloud DDNS name and I am getting ping reply from the correct public IP addeess.