BGP Flapping / Carrier issue

[RJ1]

I am running a SDWAN infrastructure with one Hub and several spoke (15 spokes). All sites are equipped with FGT  clusters running 7.2.x. we have ADVPN configured with iBGP running over it for route advertisement .On 4-5 spoke sites  I have a strange behavior that is every 2-3 days   have this error in router events logs as below:

BGP: %BGP-5-ADJCHANGE: VRF 0 neighbor 192.168.88.254 Down Hold Timer Expired

BGP: %BGP-3-NOTIFICATION: sending to 192.168.88.254 4/0 (Hold Timer Expired/Unspecified Error Subcode) 0 data-bytes []

BGP: %BGP-5-ADJCHANGE: VRF 0 neighbor 192.168.88.254 Down BGP Notification FSM-ERR

BGP: %BGP-5-ADJCHANGE: VRF 0 neighbor192.168.88.254 Up

The problem is that during this event all connections from spoke to hub are shut during roughly 60 or 120 sec

[DUSTINREEVES]

We did that in addition to removing "redistributed connected" and "redistribute static", our thought process was we needed to make sure the only things we put into the route table were intended to be in the route table.  We are wrapping up our deployment now and I still see BGP flap's in our logs, but 99% of those are chalked up to cheap broadband / cellular connections.