Once a day, iptables rules are reset, how to solve?

Question

Debian

In general, the problem is this.
There are two servers, the first one is on debian 7 (x64), the second one is on debian 6 (x64)
The problem is that once a day in the region from 3 to 5 am, the rules in iptables
are reset. At the same time, the servers are not rebooted, the rules fly off by themselves.
How to solve it?

Answer 1

first check all the rules of the cron rule

Answer 2

rules crash on both servers? how many interfaces and do they fall?

Answer 3

View logs for this time interval. Something is obviously crashing or restarting.

Answer 4

The fact of the matter is that no failures occur, except for the fact that IpTables resets the rules. I have only two rules there, they reset, at the same time on both servers at once