SNAT-DNAT:Exceptions found while Updation Of Router With External gateway info, Disable SNAT And Enable SNAT

Steps to reproduce
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Create the external network and subnet
Create internal networks N1 and N2 with each network having one subnet each.
create security group and create ports with this security group.
Boot four vms on two computes.
Create a router and associate the subnets to router
Update the router with external network(associate external gateway with router, SNAT=true, single ExtIP)
Disable and enable snat.Warning messages generated here.