Registration times slow

Hello. We are using an EG-91-NAX module. We have great service and everything generally works fine, however when we insert a SIM into the module the full registration time takes about 40 seconds.

When we insert the same SIM into an iPhone it takes about 4 seconds.

Why is this? And is there something wrong with our module?

Hello, may I ask if the module is connected to the antenna? If not, the antenna signal is very poor and the search will be really slow.