Model :

Hardware Version : Not Clear

Firmware Version :

ISP :

I've installed the product in question, to take advantage of two ADSL lines in load balancing and possible backup in case one of the two lines fell. Apparently all right after practice.
Today there was the "real" case. I had a problem with the main line, but the router has not played its role as a backup. Actually, the main router seemd to be linked but the line came and went (modem lights indicating an active link).

To allow the navigation I had to physically disconnect the malfunctioning modem.

I wonder ... what kind of control does the TP-Link whether, despite the line is not functioning, continued to rely on that, impeding navigation? Enough for him to feel the presence of the modem? It makes connectivity checks effective? Or is there any parameter to be set?

Thank's