At my families home and warehouse we have to use Netcom's 4G network to have a usable internet connection. We use a Huawei B593s-22 router for this.
With the APN information Netcom gives and the default settings for their network, all incoming traffic are blocked.
This is very annoying as I have some servers and computers I want to connect to.
Fortunately, Netcom has an alternative address that can be used.
Netcom wants you to use: internet.netcom.no
But if you want control over your own internet connection: vpn.netcom.no
Netcom is probably using NAT on its mobile network. But they have been kind enough to create VPN so users that need VPN can have public IPs and no restrictions.