You have set up everything correctly.
The log file no longer works with the latest ViX images - it used to work with the old ViX versions from some time ago, but no longer.
You should now look for two files in the var/volatile/tmp folder. The file called inadyn-ip.cache should contain just one line showing your latest IP. I also suggest you use a quicker time interval than 600 minutes, change that to 60 minutes.