When GRE tunnel is down, affect other interface connections

[nexys]

Hi,

I've been having an issue with a GRE tunnel.

My firewall recieve all my traffic trought WAN interface.
On this WAN interface I have multiple Virtual IPs.

I use one of the Virtual IPs for a GRE tunnel with an external server.

When this external server lose connection and the tunnel start having high packet loss on the Interface Monitor, this packetloss caused by the external server network, starts closing already existing connections during the downtime of the external server until the GRE tunel is recovered.

The issue is that the existing connectons were created by the other Virtual IPs wich run only on the WAN interface, not by the GRE Interface that is created when you assing the tunnel to a gre* interface.

Any recommendation?
Should I have a secondary WAN interface?
Why this is happening?