LTE modem with passthrough of external IP address

Question

Hi there. I am having some challenges in terms of finding a suitable LTE modem to use with Sophos XG. I currently have a Huawei B882 hub that is connected to an ethernet port on the computer running XG. Unfortunately the problem with this device is that it uses NAT and lacks through a passthrough mode (i.e. so the external IP address is not presented to XG). In other words, the usual problems arise with double-NAT. 
 For some reason, I seem to be having trouble finding a suitable LTE device that has a passthrough mode or is just a "bare" modem. I'm in Canada, and the devices offered by my service provider include the following: 
 
 Novatel Wireless MiFi 7000 
 Novatel Wireless MiFi 6630 
 HUAWEI LTE E8372 Hotspot Turbo Stick 
 ZTE MF275R Turbo Hub 
 
 I looked into each of these devices and it appears none of them have passthrough. The Huawei device seemed promising because it happened to be on the compatibility list for XG, which I thought was interesting because I would have thought the double-NAT issue would still arise. That being said, I was a bit hesitant to purchase it to conclusively find out. 
 I was just curious how others manage to deal with this particular issue. For example, does the XG have something to manage this when using dongles (in contrast to the hub I'm currently using)? Is there a way to configure things to avoid the problem? Any thoughts or suggestions would be most appreciated.

HuberChristian · Accepted Answer

A year ago, I evaluated a device for the same requirements. We are recommending Zyxel LTE4506 to our customers. This device can act as a bridge, passing trough the ISP's "public" IP Adress. 
 Public in "" because ISP in Switzerland often do not give you a public IP in 3G/4G. If your ISP does different, you'll feel lucky with that device. 
 
 Edit: I've just seen 3 of your Devices mentioned in your post above are USB-3G/4G Sticks. For professional environments, I'm strongly disadvising to use kind of these, because they are known to cause problems with firmware etc. etc. Using a 3G Router with RJ45 Interface can prevent you from any of those problems. Even if you use XG Firewall in Cluster mode, this Solution is still suitable.

dma0 · Answer

In case anyone is interested, I ended up purchasing a Netgear LB1120 LTE Modem. It has a bridge mode that exposes the external IP address to Sophos. In testing it attached directly to a PC, worked like a charm. 
 Unfortunately one issue I have with it when attached to the Sophos is that it seems to be going up and down every few minutes. Checking the dgd.log file indicates that pings keep failing (then succeeding, then failing, etc.). Not sure if that's an issue with the modem, the LTE carrier or Sophos. I've tried tweaking the MTU to 1476 (as recommended by the carrier) and changing the ping IP address to a nearby dedicated ping service provider, but neither seems to have helped. Rather unfortunate. If anyone has any suggestions they would be most appreciated.