Zerto WAN Traffic pausing causing very high RPO

We are running Zerto 7 update 3, and we are replicating to a Zerto Cloud partner.  We have 4 VPG’s configured and three of those are replicating and meeting RPO.  The fourth VPG has never been able to meet the RPO of 15 minutes, and the closest we have come is to within 5 hours.  Most often, the RPO is 10 hours or higher.    Anyway, we have worked with our Zerto Cloud partner without success, and we had a Zerto Engineer try and troubleshoot the issue.  On our Dashboard, we can see the WAN Traffic peak for 6 minutes and pause for 15 minutes.  The traffic is consistently performing this way.  We can’t seem to narrow down the issue with the traffic starting and stopping.   With respect to the 4th VPG, it contains our ERP SQL Server.  However, we have a 1GB Ethernet connection, and we are never exceeding higher that 40% Utilization.   At this point, I have read several articles regarding “Replication Pause Time” relative to the  Journal History.  We are seeing warnings that our “Journal History has less than 75% of the configured one day”.   Finally, I do believe that  our problem is related to a Zerto issue, because we have worked with our ISP and Zerto Cloud partner in troubleshooing our WAN connection.  By the way, we are connected via an IPSec VPN tunnel to our Cloud Provider.  We have 13 other tunnels to various offices that never have any disconnect or traffic issues.