@Hank21 Thank you for helping. Without the Block-All, so just the WAN-IN Allow rules for ports 500 & 4500, the VPN connection works without any issues. Add the Block-All, and then it doesn't connect...

I have setup L2TP/IPSec on an ER605 (v1 hardware, 1.1.1 firmware) connected to a Huawei gateway with UDP Ports 500 & 4500 forwarded to the ER605. With no other changes, (ALG IPSec is on by default) a...