Is there a time out for how long before another request is made from the controller?
I’m running a homebuilt Untangle UTM which in not only a firewall, but has modules for Webfiltering, Virus Scanning, Spyware Scanning; Application controller, IPS and ADBlocker. Here is what I’ve found so far. If I turn off all the modules but the actual firewall the Wunderground stat page goes up by 1 or 2 calls and then stops. Meaning to me the controller received its response and won’t call again for another 15 minutes. However if I turn on any additional module which scans the traffic; it doesn’t matter which one; I can watch the call counts go up by about 2/minute on Wunderground. Once I turn the module off, the call counts level off. From what I can tell the traffic isn’t being stopped by the UTM, but it’s possible the small delay introduced by scanning the traffic may be enough that the controller is thinking that it won’t get it’s response and then sends another request out.
I am going to leave everything off on the UTM except the actual firewall module to see what happens over the next day. If you could check your logs again to see how many calls are coming in from controller; I’m thinking it will look correct now. If that’s the case it is something to do the UTM, either a delay or it’s changing something in the traffic.