I was setting up a L2TP/IPsec tunnel with a 7.1beta6 device on one end, and a 6.49beta46 on the other. After the interface was created after connecting, the v7.1 router crashed and erased the whole configuration. Luckily for me, I had made a backup the day prior just in case something like this happened. How could this have happened?
You are using beta software. It warns you to make backups, and it may be unstable.
It is known that for certain configuration changes, the v7 beta crashes and resets the configuration.
This may also happen when you upgrade to a newer v7 beta, it happened to me as well.
Luckily, you can now do a /export and save it. That did not work in an earlier beta.