Double NAT and Xojo Web

Xojo Web really really dislikes being in a double NAT situation. Especially with multiple users coming from the same LAN.

Does anyone know of some JavaScript or some way for those Xojo web application to detect double NAT?

I would like to check for double nat about a millisecond after XOJO already checks for unsupported browsers. (and tell the user to fix the damn network before they can login)


No- there’s no way to detect a double NAT scenario from a browser. It’s really complicated and generally unreliable to detect automatically in general. Typically you have to be a client on the network and check the address that the client gateway itself is connected to (which would mean logging into a router, etc) You can see write ups like this if you want to know more:

[quote=279359:@Jay Menna](and tell the user to fix the damn network before they can login)


Lets not forget that whilst undesirable, there will be instances when your client cannot fix double NAT.
Many low cost VoIP adapters are designed to sit between the Internet and the clients primary router. I’m not saying this is the way it should be, it is however the way it often is. In these instances creating separate port forwarding rules on each router so that incoming traffic is routed through both layers of NAT will work around the issue.