As of 13:30 on July 25th (yesterday), MDWS had started receiving a lot of invalid, zero, data (thanks to Tony for the heads-up), and displaying that data is zig-zag graphs (eg the SNRM one).
I'm not sure why - both the machine sampling the stats (via HG612 modem_stats) and the router have been up and running just fine. They are connected via wired LAN, and a ping from PC (Windows 7) to the router (Billion 8800NL) has performed flawlessly for the last 10 hours, since about 2pm).
If I telnet into the modem (on a different computer), the modem responds just fine, and gives responses to commands. All pretty normal.
When I look at the "modem_stats.log" file, the records are missing for the same minutes that MDWS is getting all-zero data uploaded to it. That is - the file has no line for that time, whereas MDWS is receiving zeroed data.
Then ...
I tried telnetting into the modem from the PC which collects the stats. It worked fine at first, and I could issue a "--stats" command. However, while I was scrolling back and forth, the telnet window (I'm using Putty) just disappeared ... no warning whatsoever.
So I brought the Putty window up again, telnetted into the modem, ran a couple of commands ... and after a short while, the window just disappeared again.
I tried a few more times over the afternoon, with the same result.
Then ...
I left things alone, intending to go back in the evening, and all the failures just stopped around 7pm. I wasn't doing anything with that machine at the time things fixed themselves.
Now, when I go back and bring up a Putty terminal, it stays up. It doesn't just disappear. (And, while I'm still logged in, the modem_stats collection continues unabated).
Perhaps this will tell someone something about one reason why invalid data can be sent to MDWS, relating to a crashing Putty terminal.
Unfortunately ...
My PC is still somewhat stuffed with permissions, so it is still running old versions. In fact, something is also mucked up, because the GUI doesn't think there's a stats task configured, but it is running in the background.
I'm about to shift to monitoring via a Raspberry Pi, so I guess I won't get much more ability to try any fixes out. Sorry!
Then ...
I noticed some small gaps in the graphs - for example, they are at 20:14, 21:14, 22:14. Those don't get entries in the modem_stats file either, but they don't seem to cause the zig-zig graphs; just a gap.
Those gaps seem a little too regular, so I suspect they show a different kind of fault.