I ordered the router GL-X750 and want to insert a Telekom SIM card and the router is showing" SIM card not detected". I tried with two different routers from the same model and it’s still showing the same message.
What is the size of your SIM? nano, micro?
Are you using a SIM card holder? Generally this problem is caused by the physical contact. You can insert a small piece of paper to the back of the sim so that it contact well in the slot.
I have the same problem, but it says connected, shows the green light and the icon 3G/4G icon is also green. It says “sim card not detected”, but it has even uploaded 96KB of data…
I just found the solution, I did a modem reset and it worked