I installed a fresh Openwrt on Archer C20. After I got mwan3 successfully working from the router's local network, I cannot reach the outside of the wan - no port forwards or ICMP reply. This was on the 21.02 snapshot. I remember a couple of years ago I have done similar setup on 15.01 Openwrt and there was no problem with outside of the wan. Back to the current topic - I am able to ping the wan interface from the router's internal network. I also checked the firewall, which is a copy of the 15.01 configuration.
Is there a way to diagnose whether the packets are lost in the mwan3 routing? E.g. verbose logging of the mwan3 interface? Or has anything been changed since 15.01 regarding mwan3 wan configuration?