It’s possible to use this GSM modem with local Blynk server?
There’s a few of issues you’ll face…
The device you use for your server will need to have drivers available for the USB interface of the E3372. Not an issue if it’s a Windows 10 machine, but I don’t know about other devices.
You’d normally need forward the ports to the machine you’re using as your server. I don’t know how this would work with the device plugged into your server.
You’ll need to use a DDNS service like No-IP.
The server is constantly talking to the app and devices, so data usage may be an issue.
Some mobile providers appear to block Blynk data, especially Vodafone in a South Africa.
I think I would consider using one of the HUAWEI travel routers that take a SIM card and give the option of port forwarding and simply provide a Wi-Fi network that any device could connect to.
Don’t forget that your ‘local’ server could be anywhere in the world, so locating it in a location where there is a good internet connection is an option.