It probably is not the fault of your mobile broadband Router – it is usually down to the mobile network dropping the connection. This is because 3G, 4G and 5G mobile broadband services are an always available and not an always on service.
If your router, which is in a static location is connected to the local 3G/4G/5g network base station after a while the mobile network will reach capacity and when a new user requests a 3G/4G/5G connection they will have to drop one of the other users to allow the new connection.
When this happens, your router can still see the mobile network and the network tells the router the network is available, but the network will not pass any Internet traffic.
THIS IS WHY YOU NEED PING REBOOT.
Many M2M (Machine to Machine) 4G and 5G Routers will have a configurable section called Ping Reboot, Cell ICMP Check or Network monitoring. It is this section of your M2M Router that you will need to configure so the router can periodically check that there is a connection to the internet, not just a connection to the mobile network.
An example of this is that you configure the router to ping an IP address that you are fairly certain will be available 100% of the time, maybe something like Google Public DNS server (126.96.36.199) perhaps every five minutes. if the router does not get a ping response then the router can reboot and re-establish the connection. Many M2M routers also give the option of Pinging more than one IP address so this will ensure that if the Internet connection is still live, but it is just the IP address that is unavailable the router does not reboot unnecessarily because if it does not get a response from the first IP address but gets a response from the second then the router knows the Internet connection is still available.
Because of the way that the 3G/4G mobile broadband service works and disconnects users this means that there is no way with a single connection you can guarantee 100% uptime but what you can do is ensure that you do not need to drive to site to power cycle your router which can be expensive if you have to do that once a week or even once a month.
Some examples of 4G and 5G routers that include this feature are listed below :-
This means that these routers can be deployed in remote locations with the certainty that they will be able to recognise that they have been disconnected by the mobile network and to re-establish the connection.
These routers also feature an extra resilience option called SMS Reboot which means that if for some reason the automatic ping reboot fails you can send an SMS message to reboot the router manually and even send an SMS message to obtain the status of the router.