@ZdenekM 

Hey

Apologies im working from memory at the moment so this may be vague  :)

Its likely the detection of the drop out, namely its on Auto detection.   On your interface under load balancing there should be a section called online detection or something like that.  

Go in there and check the settings for WAN 1 (the primary).   its likely on AUTO.  Basically this is a ping command and on auto it will ping the device connected to that port, if its a modem the ping will fail when the wan is down.. however if its a device with DHCP (like an ISP router) the ping will always come back good  (192.168.1.1 or whatever the device is) despite the WAN on that device being down.    Basically the ISP device is giving a WAN reading, its saying LAN is ok.. 

To fix this try changing it to PING and setting it for something like 8.8.8.8 or netflix or amazon.. that way if the WAN is down its DOWN.. and ping will fail, therefore it should fall over. 

Hope that helps!!

  @Philbert Thank you for your response! Unfortunately, when the router is managed by the controller, there is no such setting (or I couldn't find it), one can only set interval for online detection or disable it. I think it is only available in standalone mode. And yes, both my WANs are connected to DHCP.

@Fae From what I have seen, it seems that one can set an online detection method when the controller is in standalone mode. But when it is managed by the controller, there is no such setting, and the default one does not work when WAN is connected to, e.g., the provider's modem. This means that my backup connection is useless because if the primary one fails, it won't switch to the backup one. Is it possible to set the method, for instance, in some configuration file? Or would it be possible to add this setting or change the default method? Many thanks. I'm working from home and need a reliable connection :-)

  @Fae Great, I could not find it before. Thank you.

  @Fae Could you please also elaborate a bit on what is the difference between "Line Backup" and "Always Link Primary"? From the description, I'm not sure... Also, "Line Backup" is there twice, which is a bit confusing.

And a suggestion - if a WAN interface is configured to get IP through DHCP, maybe the online detection could be switched automatically? Or could the user be warned, so they have a chance to fix it? Otherwise, one will realize too late that failover is not working. 

@Fae  Yesterday, my primary WAN was out for some time, but switching to a backup connection took like 8 minutes - see the period between "WAN is down" and "Logs were mailed" (successfully). With the online detection interval set to 1 minute, I would expect that after at most 1 minute, it will switch to a backup connection... What could be the problem?

PS: Also, it would be helpful if I can somewhere check the current status - e.g., "the primary connection failed, switched to backup at hh:mm".  Currently, there is no such event (should be, I guess, but I've never seen it), and I have to check the status of the primary/backup WAN in the details of the router. The status of the connection is something I would like to see on the dashboard, as it is quite crucial. And it should also be visualized on the Map - I have two connections, but there is only one connection to the internet. There should be two, and one could see which one works and what is bandwidth.