Antivirus scanner definition file update failed due to download failure. Check your Internet connect

I have been using RN214-4 bay for several year and is running as a NAS on a hardwire/wireless home network all running Windows PC, Apple phone/ipads, connected printers, TVs, home audio (DLNA and Itunes).  OS is current at 6.10.3. I'm able to check for OS updates. I'm also able to turn off and then turn on clock sync.  So it appears the RN has internet access.  I also get emails every day regard its operation, defrags, etc. 

However I continue to get an email every day from the RN :  "Antivirus scanner definition file update failed due to download failure. Check your Internet connect"  The status light on the antivirus has now turned yellow on the System\Overview device screen.  

I recently had to change my Frontier FIOS router.  Before and after the change the RN runs a static IP address.  I think the Antivirus scanner definition update failure coincides with the new router.  I have rebooted both the router and RN several time in different orders.  I have looked at the router to see if the firewall has a log that I can compare to the time of the RN email relate to the antivirus definition and can find no log to review. Firewall settings are default on on low. 

I'm not a tech / software / network person by so please keep that in mind.  

Thank you to anyone in advance for any help you can provide.