Windows 8.1 no internet connection issues

[crabber]

I am using a laptop with windows 8.1 in a place where the only possible internet connection is by using a mobile phone sim card/data package in a usb dongle.

My problem is using the same laptop to locally connect to an RS485 serial to ethernet converter which is monitoring a solar power system.
I am using a crossover cable from PC to converter. If I use an XP PC I can connect and the monitor program runs without any trouble whatsoever.
However with windows 8.1 I get the irritating message "limited or no internet connection" which of course I already know !!
I can log in to the converter from a browser using it's local ip address, I can ping the local ip as well.
The monitor program uses ports other than 80 and will simply not connect.

I have tried much research, learned how to change public to private networks, disabled firewalls etc etc but cannot make it connect.

[crabber]

Update: all sorted now, the software I am using for monitoring called Aurora Communicator was (I think) the problem, I was using version 2.9.2 which came with a CD but downloaded later version 2.9.21 which does work.
Hope this may help someone but it is possibly in the wrong section.