Weird things happening with a server

1. 7.7.7.x is NOT a private network!!! Yes, it can work if you do proper routing rules, etc, but there are enough private subnets to use and you should be careful and leave the public subnets alone. The private subnets are 10.x.x.x, 172.16.x.x and above, and 192.168.x.x.

For example, 172.10.x.x is public, but 172.20.x.x is private.

So, I suggest you change the 7.7.7.x to something like 10.10.12.x.

2. No need to use the 'network' option in /etc/network/interfaces. It is calculated from netmask automatically. It only creates possibility for an error. In fact in your case I think the 'network' option is a problem because you use netmask 255.0.0.0 and not 255.255.255.0. In such case the 'network' value you are using is not correct.

3. Related to the above: If you plan to use a subnet like 10.10.10.x better to use netmask 255.255.255.0, not 255.0.0.0 like in your case. It splits the subnet more appropriately.

4. You use only one gateway, not on each interface. Unless your setup needs it, but in this case I think it doesn't.

So, with all of the above, change your three private interfaces to:

address 10.10.10.250
netmask 255.255.255.0