Should this connect to Socket on the other hand ( desktop app ) or it should use web socket for example
It can be any TCP or UDP server that's accessible to router.
The original problem was that your VB6 application did not receive NMEA data from the router on port 100. So, does it work with 192.168.1.102:100? If still not, can you do some tests and send me some more files? :)
For diagnostics I would need a tcpdump file and another Troubleshoot. (Both can be downloaded from the same System → Administration → Troubleshoot page.)
About tcpdump:
A tcpdump (pcap) file stores packet data and could provide useful information for analyzing where (if anywhere, in this case) the packets are going. However, by default it doesn't save any information so it has to be enabled and configured first. For your case please configure it like this:

About the Troubleshoot:
It contains the router's logs and configs among some other things. However, the router saves the logs in RAM. Therefore, it is cleared if the router is rebooted. So in order for me to see any related errors, the Troubleshoot has to be taken after an error occurs and before rebooting the router.
I recommend doing everything in this order:
- Configure NMEA (if not configured already)
- Configure tcpdump
- Start listening for connection on the app
- Reboot the router
- Wait for the router to start and login to the WebUI
- Check to see if the router has obtained a GPS fix
- Check to see if the app receives the NMEA data
- If not, download the Troubleshoot and tcpdump files and send them to me
- If yes, then there's no issue to diagnose
about the SIM cards if the first SIM card fails should the second one connects automatically ?
It will not connect automatically by default. It has to be configured first. Info on that here.
my goal is to keep my video streaming up & running if the 1st SIM fails the 2nd SIM would be alive and no offline appears to my apps
is it possible?
It's possible, but I must say there will be at least 30 seconds of downtime in between when the first SIM fails and the second one comes online.