I followed Bernt's guide to establish the internet connection with Huawei E3276 on RPi 3 and it worked like a charm. However, I can's figure a way to open port in Huawei E3276.
My ISP claims that they disable the firewall for me hence it should not block any port, but any of my port has been opened according to www.yougetsignal.com/tools/open-ports/.
I try miniupnpc and Upnp Router Control but none of them can recognise E3276 .
