@Sunshine I live in Italy I have two ITALIAN SIM cards one is TIM and one is LYCAMOBILE TIM SIM WORKS PERFECTLY ON THE ROUTER. and other sim does not work in to the router THE VERSION OF ROUTER IS...

my tplink MR6400 works perfectly in Italy with TIM sim but if I plug in LYCAMOBILE sim it doesn't detects the SIM card tried updating to let latest firmware but doesn't work tried applying APN...