Question : Problem: Where can I find a diagnostics software to test the modem? I am not interested on speed test, but rather on basic equipment functional status.

I have a SpeedTouch 780WL DSL Modem. The WLAN light simply went out, and from there on I can not connect to the internet. I then connected via an Ethernet cable and it connect OK from the laptop to the modem. The Internet and DSL lights are solid green. The ISP indicated that the service is up, my account is up to date and active. I checked my house cabling facility and it is OK. I need to demonstrate somehow to the ISP that the Modem is not working without having to be another 2 hours thru a help desk session.

Answer : Problem: Where can I find a diagnostics software to test the modem? I am not interested on speed test, but rather on basic equipment functional status.

I don't see how just software results can show your ISP that the modem's wireless connection is bad. Just tell them the WLAN light went out and it won't connect you to the internet wirelessly anymore... that you connect using the same computer with a network cable just fine. Take your computer to another location with a wireless modem/router/access point, if possible, and confirm that it does still work wirelessly, that way a) you can tell them for certain your computer's wireless works properly, and b) you can be sure after you convince them to come swap it out they're not going to get it back to their shop and have nothing be wrong with the modem.

We can presume you already did a cold boot on it? (e.g. unplug its wallwart/power supply for 5 minutes, then plug it back in, press the 'on' button if necessary, and see if all of the modem's lights come back on after a few minutes.)