Wan-Link Manager shows wan down, but in reality its up

Changing the MTU isn't working. Also, if i try to change the failover rule for the first WAN (Airtel one), it shows the following error: 'Gateway failover rule could not be updated'

What is the reason for that?

Hi,

please review each setting in the WAN manager settings in networks to see if the destinations are still active, after correcting any errors please try restarting the XG.

Ian

Still not working 

Please check each address you are using to test, try using the ip address of each interface as the fail test network. Please post a copy of the wan link manager settings.

ian

Tried changing the Ip, but am getting the following error: 'Gateway failover rule could not be updated'

Please post a copy of your wan link configuration.

Ian

When i try to add another condition, I get the following error:

what device has 254 has its address? I asked you to change it to the WAN interface address which is 1.15.

Ian

Its the isp router. 1.15 is the ip of my nic