SITE to SITE VPN keeps disconnecting

[Lionfresh]

Hello Experts, I need some help in resolving this one....

I have a FortiGate 60D at my head office and a 30D at my remote site. I configure a site to site VPN which has been working for over 3 years without any major issues. During this time my ISP was the same for both sites and the bandwidth was the same...

A month ago I change the internet provider for one site and increase the bandwidth. so now my bandwidth at the head office is 20MB and at the remote site it is 10MB with ISP x at head office and ISP y at the remote site... I reconfigure the VPN link after this change and the tunnel was up and running without any problems until yesterday persons started complaining at the remote site that they can no longer access anything thought the VPN(shares folders, ip phones). when I checked I realize that the VPN connection is dropping. I would connect for about 2 mins then drop and it has been doing this since. I have restarted the FortiGate at the remote site but the same thing continues to happen.

Anyone would know what could be causing this? could it be the fact that one site is 20mb and the other is 10mb from 2 different providers? Please guy I really need some help... Appreciate all suggestions

[Sudarsan_Babu]

Hi,

Run diagnose debug . This should be done when issue occurred 

diag debug disable diag debug reset diag debug app ike -1                         <<<<<------------- ike -1 or ike -2  diag debug console timestamp enable diag vpn ike log filter clear diag vpn ike log filter dst-addr4 X.X.X.X <<<<<-----------Remote peer public IP diag debug enable