I have 6 Buffalo-Tech’s WHR-HP-G54 (with the latest firmware — WHR-HP-G54 Ver.1.40 (1.0.37-1.00.0.03-1.04)) installed at a shopping center to provide wireless Internet hotspot. Since these access points (AP) have to be accessible from my office LAN, I set their default gateway via the web interface. Apparently this didn’t do the trick, I couldn’t access nor ping any of the APs from my LAN.

I used their Ping Test page to test connectivity from the APs to the router which is set as its default gateway, they received replies from the router and are now accessible from my office LAN.

After a few hours I wanted to change something via the web interface of the APs, but they were no longer accessible! Ping from my LAN to the APs ceased to work again, then I tried to ping the APs from the router, which is in the same network as the APs, and I got replies.

Knowing that the APs are actually still accessible from the router, I installed tinyproxy on the router to get to the APs’ web interface. I found a trick that triggers the firmware not to ‘sleep’: set NTP server with 1 hour interval. Why 1 hour? Because when I used 2 hours or more, the firmware still went to ‘sleep’ until the next NTP synchronization. Since I wanted the APs to be accessible at any time, I set them to 1 hour and voila, no more ‘sleep’ing problem! 🙂

Update (Nov 23, 2007):

I got this one wrong, sorry. 🙁
The firmware is fine, there is nothing wrong with Buffalo-Tech’s WHR-HP-G54 latest firmware. I found out that the tunnel interface on my Linux server created by ChilliSpot caused this behavior. If devices behind this tunnel-bound network interface do not initiate any connection then they will not be reachable from outside (despite having correct routes on the server). The only way to reach these devices from outside network is by getting them to initiate something. In my case, the hourly NTP synchronization schedule that I set on my WHR-HP-G54s triggers something which initiates a connection every hour allowing these APs to be ‘registered’ and reachable from outside network.