Zte mf910 broadband router

Hi,sorry my bad english, I am from Finland. My zte mf910 broadband router stopped working it does not connect to internet, it gives this error ( “error number”) when you try to connect. I found that the zte software update is out of date (old) and cant update(upgrade) it when it is not connecting. The zte worked with ubuntu 16.04 but not now with ubuntu 18.04. Now I have old huawei stick with the same simcard that I used with zte and it works ok. Can anyone tell something about this problem?

First, check out the manual. Second, reset the device to factory settings.