Dear @Cld,

When In failover mode, is there a way to know which wan connection is in use (at the moment I need to use a web site to check the public IP address, which is not too convenient. failover seems to work fine, but the router does not seem to go back to primary connection when it becomes alive.

To know which WAN connection is in use, you could log into the web management page of the router, go to Status to check which WAN connection is Link up, OR go to Online Detection to check which WAN connection is Online.

also is there a way to record some logs (I would want to know when wan connections are switched)

If you have a server to save log info, you could configure the log settings to make it.