RepRapFirmware for Duet Ethernet Frequent Disconnects of DWC

Hi all,
Hoping to get some insight into an issue I am having. Here is the info first.

The printer is a Fusion3 F410.
Firmware Name: RepRapFirmware for Duet Ethernet
Firmware Electronics: Duet Ethernet 1.0
Firmware Version: Fusionware 1.18.1 RC2 (2017-05-15)
Web Interface Version: 1.19.3
Web Interface by Christian Hammacher
Licensed under the terms of the GPL v3

The issue I am having is I am getting frequent disconnects with the DWC, Windows 10 with Edge.
This is a replacement printer. The first machine did not have this disconnect issue. Board and firmware etc. should be the same as the first printer.
I am using wired Ethernet connection with a static IP assigned in the printer. Same configuration as the first printer. No changes to router or switch.

I get the typical AJAX disconnect message but the reason given is "unauthorized" rather than timed out or anything else.
This can happen while prints are running or if the printer is sitting idle.

Thank you for any advice and I can try to provide any additional info that may be needed.

Firmware 1.18.1 is quite old and normally I would recommend upgrading to either RRF 2.05.1 or RRF 3.2.2. However, Fusion 3 uses their own fork of RRF and I don't know what consequences might follow from changing to a standard build of RRF. You might be able to find someone else who has tried this if you ask on the forum at [forum.duet3d.com].

Are you using a password on the machine? I can't think of any reason for getting an "unauthorized" message other than that there has been a reconnect and the firmware thinks that the password.is incorrect.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks for the insight.
I knew they used there own fork so am rather reluctant to change anything, replace firmware or DWC, at this point. Also some warranty left!

Yes the machine has a password for the DWC. Odd thing is I didn't have this issue with the previous machine. This one is a warranty replacement.
I also thought the "unauthorized" message was odd.
I'll keep digging and see where I end up.

Here is the error I get.