My router is an MR400 V4.20 EU. I was told that this router can work with my mobile carrier, but when I plug in the card the router cannot even detect the network. Card works fine in my phone. Other sim card, other carrier works fine in the router. I've checked, my carrier is using band3 and MR400 does work with band3. I've set up the APN correctly but until there is no network/signal detected it is useless. I've upgraded the ISP file with the latest, still no network. I don't really know what the ISP file contains. Maybe the APN data? How can I check if my router knows about a carrier? How can I make the router work? Right know it looks like that I've just wasted my money on this device. I had big hopes to attach an external antenna to it and boost the signal on a different location where the carrier signal is very week because of high building.