XB7 - LAN Connection to/through Ethernet Ports on XB7 Dropping

So this is a tad frustrating. 

Just upgraded my years old XB6 to an XB7. I'm a week into using the new XB7 and it's been a challenging little bugger to say the least. 

With this post, I'm making a make a list ditch attempt to resolve the issue.  

Setup - Please remember I had an XB6 and all was well before the Xb7 upgrade. I have two switches connected to two GigE ports on the XB7 (as I did on the XB6). I have a newish 2019 MacBook connected directly to the 3rd port. The 2.5Gbps port on the XB7 is vacant. Hanging off of the 2 switches I have normal things like NAS, HUE, Alarm, Security Cam's, etc. A total of 57 devices of which 18 are physically connected via Ethernet.  

Behavior - The XB7 LAN connections that both transit (switch) through the XB7 and route outbound are randomly disconnecting and reconnecting. Some take minutes to recover, some never recover without an XB7 power off restart.  

Example - I was on a zoom call, via the MacBook, directly connected to the XB7. It dropped. I Could not ping the gateway or google (8.8.8.8) nor could I ping LAN connected devices. If I didn't have link lights , I would have thought that the cable was physically pulled out of the Mac or XB7.

If I disconnected the LAN cable between the Mac and the XB7 Ethernet Port, wireless would take over, and boom... I was back up. Wireless is stable (and has remained that way). Plug it back in, link comes up, connection drops - can't ping anything. 

I hard reboot the XB7 and MacBook, and all is well. I can ping. A soft XFi app restart doesn't seem to work.  

In one instance, while running a recurring ping to the GW (10.0.0.1) , NAS, and Google (8.8.8.8) in 3 terminal windows, I went into the XFi app and unpaused our Apple TV (wireless device) to let my kids watch it. As soon as I clicked Unpause, all my ping sessions stopped connecting from ther MacBook which was physcially connected directly to the XB7.  I have not been able to recreate this behavior though. And the cause and effect might be random, and this finding only anecdotal. 

I'm getting a ton of email alerts from my NAS that it was disconnected from the internet (Synology). It's happening at random times of the day - some in the middle of the night.  I've never gotten these errors before. I get 4 or 5 a day now. These are only sent when the NAS can't connect to the internet for a prolonged period of time. A router reboot lasting 10 minutes would not result in this error. 

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Connection to XXXX.synology.me has been lost since 2020-06-23 04:10:03 -07:00

Dear user,

Connection to XXXX.synology.me has been lost since 2020-06-23 04:10:03 -07:00. Please check the network connection of your DiskStation, and make sure its DDNS service is enabled.

Sincerely,
Synology Account

This is an automated email, please do not reply directly to this email.
If you need further assistance, please contact us via Synology Account.

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While wireless connections seems to be strong on the XB7, and is NOT impacted by this issue, devices that directly connected via Ethernet are getting disconnected and dropping.  I'm not showing any port /speed  / duplex errors and no port errors on either switch. Layer 1/2 seems(?) intact, everything else (3 and above) fails. 

As I sit here now, my ethernet connection from my MacBook directly to the XB7 is down hard although it's physically connected.  

In addition, wireless LAN connections from a wirelessly connected Laptop to a Wired LAN connected NAS are laggy. RTT is high for ICMP (over 1000ms) when sitting right next to the XB7 with a laptop.  

I've tried pretty much everything in the book to stabilize the ports including -

- Hard coding duplex on the switch ports

- Assigning a static IP to the MacBook (switches already have static)

- Removing all devices from all Profiles in XFi

- Removing all Scheduled network "pauses" and any other rich functionality that would down or pause connections

- Swapping Ethernet Cables for devices that connect to XB7

- Switching around XB7 Ports and the devices that connect to/through it 

IT SHOULD BE NOTED. I disconnected all devices and booted everyone off of WIFI so the only device that remained connected to the XB7 was the Macbook via ethernet. With no other devices connected, I was still disconnected from the port  (or the device stopped routing for my IP). 

TL;DR - Wired Connections to and through the XB7 are dropping LAN-to-LAN, LAN-to-WAN, and WAN-to-LAN . Can't replicate what causes the problem, however,  problem is significant enough for me to spend 20 minutes crafting this message to try and resolve. Looking for ideas to troubleshoot / resolve.