Suddenly Stuttering Airplay Airport Express: ruling out causes

[Marco_Sassone]

Roon Core Machine

NUC 7 - iMac (Big Sur)

Networking Gear & Setup Details

cabled Ethernet 5e network with two Netgear LAN switches
the culprit Express base is hard wired with fixed assigned IP (10.0.1.3, which shows correctly for a short time in Roon Audio page, then switches to a mysterious 169.254.118.155 - I guess the factory assigned) and is connected with Optical Tos link to the DAC Bryston BDA-3

Connected Audio Devices

Number of Tracks in Library

Description of Issue

System has been working reliably (apart the old Airplay issues not entirely solved, but definitely made bearable long ago, since I wired the connection to the incriminated Airport Express) until yesterday, when I received a new (brilliant) hi-fi furniture, and I re arranged all the equipment on it.
Today the Optical input coming from the Airport Express to my Bryston BDA-3 DAC has become unbearably stuttering.

From the Audio page in Roon settings I noticed that that Express base is listed under ‘Other network devices’, while the other Airplay devices are all under the more reassuring ‘ROON Tested’.
Please See screenshot:

Before I start to check on each LAN cable I painstakingly laid down yesterday, I’d like to know if this
is ok or it’s a clue to what’s going wrong.
PS: the other systems attached to other Express bases work ok.

TIA

[wizardofoz (Mr Fix It aka The Wiz)]

Make sure the toslink cable is properly seated into the ape. You might have also broken the Fibre inside as it’s rather fragile

[Marco_Sassone]

thank you @wizardofoz

before doing anything else as, I tried a quick swap, placing my Apple tv in place of the Express, also using another optical cable (as the Express has the jack type).
Well, it works flawlessly.
Now remains to see if it’s the optical cable which got broken as you suggests or a reset of the Express base could do the trick.

Still puzzles me why that Express is listed under ‘Other Network Devices’ and not Roon Tested …