I am currently in this situation and I'll try to be as specific as I can. My firewall has 20 VPNs (over the internet) with different vendors. Everything was fine til a month ago.
I usually use ping to monitor the remote networks and some of my VPNs have 1-5% packet loss. The VPN does not go down, but the ping does. The firewall log shows nothing wrong, not any blocked packets everything seems all right. Overall, it is a 0% packet loss / day, but in some intervals it goes to 5% (at about 1pm, where traffic peaks) Some other VPNs are fine with 100% reply.
What I noticed:
-Most loss occours when we're at peak traffic (again, only for the "damaged" VPNs. The other VPNs are fine)
-From my WAN i have 0% loss with 220.127.116.11 but there's 1-5% packet loss with the remote WANs in question.
-Restarting the firewall stabilizes the situation for about a day, but then everything starts over again.
-The VPN tunnel is UP all the time.
any help from your experience would be truly appreciated