IKE Error, some days no connection, some days works fine

Hi,

I'm using DynDNS to connect my office PC with home PC, both linked to FritzBoxes. Most days the dynamic distribution of the IP addresses work fine but about one of every 7-10 days I get error messages and the IP address given by DynDNs does not match with the IP address seen in the FritzBox. Then I have to manually correct the IP address at DynDNS to the one shown in FritzBox and all works fine again.

How can this be avoided?

The error messages start that the connection is cut with: 3 IKE Server. Then it shows another 2 messages: IKE-Error 0x2027 and 0x203e.

Any help highly appreciated. Andreas