@jeffgaines Open this link in your browser and select your country of residence - it will show you the compatible 3G/4G USB modems for VR2100 in your region.

@RealCrashHouse Check this post for more details on that issue. Also check this post to see how you can mitigate that.

@Dave-D These hidden networks could be emitted from another devices on your network. You can determine what hardware vendor they belong to by their MAC addresses.

@Milesh This should be the tech support duty I think - at least I don't know any other way.

@Milesh You may send an email to support.forum@tp-link.com to ask for further suggestions and help.

@Milesh Sorry my bad. This setting would have mattered if your AP routers were set to Smart IP(DHCP) and you have made an Address Reservation on the main router for them. Sometimes to detect Internet...