webmin server sort of sleeping

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http://serverfault.com – This is a strange one. I have two linux servers. I have server-1 server in my office which is running as a lamp server for various things. I also have server-2 behind it on an internal ip address. I have just switched by network dhcp from windows server to my draytrek router. Now for some reason after a few hours of inactivity i am unable to access the server-1 or server-2 from outside the office until i either return to the office or until i open and ssh connection to server-1 then things just return to normal. (HowTos)