Hello, when I have attached the SIM card to the Wap R, the LTE link does not appear under Interfaces. What should I do?

wAP R (without KIT) means you have only wAP R without a LTE MODULE probably.

Go to System > Resources > USB > show us what you have got here.
Mine is:


If you not have a module then I suggest you buy Quectel EP06-E or EP06-A for America.