Be sure router firmware are latest. Try the other DNS of 184.108.40.206 and 220.127.116.11
Be sure the date and time is correct in routers and devices.
Over the last week I got a similar error on my Amazon Fire 4K box but it wasn't the box or my network. Netflix was why IMO. Rebooted and haven't seen this in a week.
Netflix issues new Netgear Router and Samsung Blu-ray player.
Never had a problem with Netflix running Ethernet connected via Access Point with older Netgear WNDR3700 router to the Samsung BD-H6500 smart player. Recently changed routers to NightHawk R7800 X4S router.
Set up like old router as access point. Can watch a video entirely but sometimes each day if I try to Remove a Netflix title from my List, play another video, or anything else I will receive the notorious... "Try again later. Cannot access.. whatever" ,messages. If I exit Netflix and re-enter on Blu-ray player I am fine.
(Note no issue with Amazon firestick and Netflix using wireless from this same router)
Never had this issue before with Netgear WNDR3700 as access point to Blu Ray player. With Nighthawk series it started. Tried 2 different firmware's .28 and .32 ,same problem.
I have reset the router to defaults and tried again after setting up as access point. No difference.
----Might try wirelessly just to see if it is ethernet connection???
IP setting are obtained automatically by the Blu Ray Player via Netgear Access Point with the Smarthub of BD player showing the correct IP gateway and a DNS server of 209.........