Thanks for your patience here!
If you haven’t yet, I would review your router settings>devices list, and ensure your devices aren’t functioning across different local subnets. It could be the case where a network reboot allows for your devices to re-connect to the same subnet your Roon Server is on.
Here’s more information to help:
Let us know your findings! 
OK,thanks you
Hello,I checked settings devices list as recommended; all are functioning on the appropriate subnet.
Hi @Michael_Ouimette ,
Did you mean to say the Netgear 8000P router here, or are you trying to connect devices to the modem directly, bypassing the router? Even if it is the same subnet range (192.168.1.XYZ), if you have two routers active (DHCP servers), then they will not be able to communicate with each other.
I am saying the Netgear 8000P;subnet range comes from this unit. I am not trying to connect devices to the modem directly. I have only one router:Netgear 8000P. Thanks.
Hi @Michael_Ouimette ,
Since the issue only happens on Ethernet and not Wi-Fi, I would focus on the router settings. Do you by any chance have “Access Point Isolation” turned on?
Hi Noris
I have ‘Access Point Isolation’ turned on.
@Michael_Ouimette - You’ll need to turn off Access Point isolation for Roon to be able to communicate properly.
Hello noris
How do I shut off ‘Access Point Isolation’ for Roon.? I misunderstood your recent suggestion thinking Access Point’ related to devices not Roon. Thank you.
You actually understood properly. Access Point isolation isn’t a Roon setting. This article should help you though https://www.gadgetreview.com/how-to-disable-ap-isolation-on-router it should be found in your router settings. I wish I could be more specific but it depends on which router you have.
Hi Daniel,
I turned off ‘Access Control’ unfortunately it did not solve the issue. Audio zones appear only after shutting off all connections by pulling the main plug.
Now that you’ve followed @daniel instructions regarding Access Control please reboot your router and report if you have noticed a change.
Hi Singleton,I wil try again. Thank you.
Hey @Michael_Ouimette,
Since a few days have passed, I wanted to check in on your thread to see how things are performing. Let us know, we’ll be monitoring for your reply! 
Hello Benjamin,Singleton,noris
No the same issue persists; audio zones do not appear. As suggested I turned off ‘Account Access Isolation’ then rebooted the router. It had no effect to resolving the issue. Audio zones only appear after shutting down the modem and router, then rebooting the system. Thanks again for your continuing technical support.
Hi Michael,
Your modems firmware is updated by your ISP I take it but what about your router? Can you check if you’re in need of an update for your model. Secondly, how comfortable are you with the idea of reseting your router to factory defaults and reapplying your settings should no other options be forthcoming at this time? You appear to be capable but its a task for someone who understands what theyre doing should you elect this option.
Hello Singleton,
I’m ok with pursuing a router reset. I assume a reset option is available in ‘routerlogin.com’ otherwise I’ll have to do some research. Thanks again.
Affirmative, you may find it somewhere on the link which you’ve provided or possibly for example starting here:
Given your valid concern on Roon functioning via WIFi yet not Ethernet I think it makes sense to examine your hardware more closely. There’s always the possibility that your router is unstable/faulty. Thats not proven of course were just testing.
Which reminds me before you even do that why not plug your devices into an alternative port on the router for a simple check to see if you have a bad port and change out the cable as well if you have one handy.
Hello Singleton, I have plugged into alternative ports and changed out the ethernet cable as well. Problem persists. I’m having surgery done today so I will get back to you in a few days after trying a resets.Thanks.
All the best Michael, be well
I’m continuing my research into your issue. I don’t know how relevant the link below is but it certainly is interesting.