Balance 20 and 20X and 4G LTE failover SIM, remote access not working

Hello everyone,

Wondering if someone can help me shed a little light or give me some guidance on how to resolve my problem.

Purchased a SIM card from Tmobile for failover WAN. Tried it in both my 20X (directly installed) and in my 20X and 20 via a Netgear LB1120 and the WAN ports. LB1120 is in bridge mode and routers are getting WAN IP address from Tmobile. Internet access available. Put in my DDNS provider in the appropriate WAN connection dialogs and verified from the DDNS provider’s website that the routers update the provider with the IP address. Also in WAN dialog enabled reply to ECMP. Setup remote access key and password. VPN passthrough enabled on LB1120, but this shouldn’t be necessary for directly installed SIM in the 20X.

Pinging the DDNS hostname and WAN IP addresses of the SIM cards fails. Accordingly, VPN fails. Tested SIM card from my Verizon phone with same results.

Any ideas?

Cellular companies use something called carrier grade NAT. It does not allow inbound connectivity.

You can see the NAT by looking at your IP address you think you have, then go to and see what the internet sees you as. They won’t match :slight_smile:

Thanks, makes sense. I guess I can depend on one of my site’s main WAN being up and then use the site-to-site if I need to get to the remote network via L2TP.

Hmmm, so I guess now my main site-to-site router is constantly updating the route tables because the remote site with the LTE WAN is telling my main site it exists and the main site can’t verify this because of no incoming connections for the backup WAN.

Wonder what’s the best way to deal with this? How can I maintain PepVPN via LTE failover?

Yes. FusionHub and SpeedFusion get around the issue by setting up a public IP out on the internet and tunneling it to you.