Hi! Have installed OpenWrt 18.06.1 on TP-LINK TL-WR1043N v5 and it works very well. I configured 2 Loadbalancing/Failover interfaces, one per Static IP and one via PPPoE.
I now have the problem that the interface with PPPoE is likely to fail and when it fails the router still tries to forward the DNS requests from the internal clients over that interface and not over the good one. The other traffic works well. When I manually restart the interface the good WAN connection works including DNS resolving.