The Proroute H750 range of 4G routers support the use of Dynamic DNS within their configuration but this is reliant upon the mobile network because the majority of mobile networks in the UK will not provide your router with a public IP address which is required in order for DDNS to work.
In our experience, the only standard mobile network data SIM card that provides a public IP address is 3Mobile and for this you need to use the APN of 3internet and set your connection to 3G only. Please note that 3Mobile do not always give your connection a public IP address and they may stop this service at any time.
In order to use DDNS with a normal mobile network SIM card you will first of all need to check that your mobile provider is giving your connection a public IP address dedicated to your connection.
In order to do this you would simply get your router to connect to the internet and then visit www.showmyip.co.uk and this will tell you your routers public IP address assigned to it by the mobile network.
Assuming you have made no other changes to your H750 router apart from the APN setting, the default setting is that you can remotely access the router using public IP address, so all you need to do is go to a PC on a different internet connection, eg. your office PC connected to wired broadband, open up a web browser and type in the IP address shown when you visit www.showmyip.co.uk and if you can connect to the router, then your mobile provider has provided you with a dedicated, public IP address and you can use DDNS.
if you are unable to connect to your router, then it is likely that your mobile provider has given your router a private IP address, and the public IP address shown when visiting www.showmyip.co.uk is using CGNAT (Carrier Grade NAT) which has a public IP address, behind which the mobile network has up to 250 devices using at the same time, each with a private IP address. This means that you cannot connect to your router because the mobile network has 250 devices with private IP addresses all behind this single public IP address. This CGNAT applies to the majority of standard mobile broadband data SIM cards obtained directly from the mobile networks. In fact the only network we know that provides you with a dedicated, public IP address is Three mobile and for this you need to use the APN of ‘3internet’ and set your router to connect at 3G and even this is not guaranteed to get your router a dedicated, public IP address every time it connects. It is for this reason that many professional M2M router installers will use a Fixed IP SIM Card service to ensure that they can reliably communicate with their router when they need to.