I have ??WHR-G300N Ver.1.82 (R1.12/B1.01)?. That is newest firmware, right? It is connected with cable to my Windows 7 desktop. My ISP is tampereenpuhelin? in Finland. I first had router switch on "auto" but now it is "on" and I am using "Acquire an IP Address Automatically from a DHCP Server?".
After about 25 minutes I lose connecttion to internet. I can't use internet from computer and ping to 8.8.8.8 from WHR fails. If I remove WHR and connect my computer directly to network there is no problems.
I can restore connection by doing "Renew" or "Check connection" from Setup menu of WHR. It also seems that when automatic DHCP renew is sent at half hour mark connection starts working. I have no clue if problem is DHCP related, I just know those fix the problem until after 24-29 minutes it happens again.