The network from hell

Core Machine (Operating system/System info/Roon build number)

Skull Canyon NUC/W10 recently upgraded to NUC8i7BEH2/ROCK. Running production Roon latest version, automatic update.

Network Details (Including networking gear model/manufacturer and if on WiFi/Ethernet)

No-name cable modem from ISP, recently upgraded to AVM Fritz 6591. The first setup had a Velop mesh attached as well, and had to have both WLANs active to be any use coverage wise. The AVM has its own mesh system, so there is now only one WLAN in the house. Professional ethernet wiring in the house. (They used CAT7.) Switches all unmanaged, without option to update firmware.

Audio Devices (Specify what device you’re using and its connection type - USB/HDMI/etc.)

dCS Rossini/Clock and Meridian 818 on Ethernet. Meridian MS200 on wireless bridge (kitchen).

Description Of Issue

Initial state: instability. The kitchen zone disappears and the MS200 seems to crash; independently the other two zones disappear too and take the rest of that switch with them (touch screen NUC, DVD player for SACD ripping, laptops).

The no-name router was inflexible in configuration, but I checked for human error. Bought cable tester, all cables fine. Bought new switch for the problematic room. Bought long cable instead of house wiring. Checked no second DHCP server, installed a tool on a fixed computer checking that constantly. Nothing helped.

First useful change was chucking router and Velop and installing the AVM Fritz router and mesh. Since then the coverage has been superior, and the wireless bridge to the kitchen solid. The MS200 Roon zone hasn’t disappeared once, nor has the MS200 crashed. Result.

The two ethernet zones have also been totally solid. Problem solved! At the cost of replacing all network hardware and testing all cables…

Or not - and this is the current state. Again the two ethernet zones disappeared two days ago, no access to DHCP server/Router, same story for everything on that switch. You can imagine the withering look from my family…

I can’t blame the switch, because I have three different ones rotating there, and they all do this. And it happens however the switch is connected to the router (house cable or loose long cable). And it happens the same for both old and new router.


One of my interim states has been a direct wire from router to 818 (to make music in the sitting room), with the switch running from the house connection. Then when the switch crashes, which it does, the music in the sitting room keeps going.

So I had a brainwave. Will the zone work through the switch with nothing else plugged in? Yes, it immediately found the DHCP server, and the room is again stable, with just three connections: 818, Rossini, router. The other devices (DVD player, 2-3 computers) are plugged into the other switch. One switch goes through the house wire, one through the loose wire. It seems to be solid.

Why would this be the case? There can’t be too many devices plugged into a switch can there? - it would be silly if there were limit which was less than the number of sockets. Could it be that one of the other devices is responsible for the switch essentially crashing? If so I am pointing the finger at the NUC (D54250WYKH1) because its USB output was so noisy that it is unusable with the 818 USB input (which can’t have much/any isolation): maybe the Ethernet connection is similarly poisonous? Is that a thing?

While I wait for this new setup to fall over as well, causing my giving up and going back to 78s, anyone have any insights into what might be happening with these switches?

You lost me… can you draw a picture?

I was worried someone might ask for that.


Pencil and paper block diagram…

What you’ve done so far is pretty much what I think I’d have done; sounds logical to me.
Not sure where the core is plugged in though.

Seems possible, even likely if what happens happens no matter which switch is used. Some device may kill the switch by over-flooding it with traffic, like through a loop that shouldn’t be there? a device that is both on WLAN and Ethernet? – no idea, really: I’m no engineer, network or anything else.

To me, that doesn’t seem to be very likely.

Maybe you have two devices in your network acting as masterbrowser, that can cause these kind of conflicts.

This is certainly above my level of understanding networks. However, I might try unplugging EVERYTHING. Then, start back with one connection and one device at a time, plugging things in as you think they should be until something fails.

Hi @Ludwig,

A network diagram would help here :slight_smile:

Based on what you mentioned though, I’m wondering if this is related to multicast and the switches not passing the traffic through properly.

Can you check to see if you have IGMP Snooping or IGMP Proxying settings on the Fritzbox router? Is it up-to-date on the latest firmware?

There was a feature called “Software Packet Acceleration” on Fritz OS7 that caused some issues with remotes, connecting, I would check that as well.

Thanks everyone for the suggestions. The solution I tentatively seemed to have found in my OP has been 100% stable since then. So, from Fritzbox router there are two LAN cables to the same room, and two switches in that room, one with just the DACs on it, the other with PC, Laptops, DVD player for ripping etc. I don’t know why it won’t play ball all on one switch, but I am still suspicious that the NUC’s Ethernet connection is dodgy (outputting with some sort of gross (RF?) noise like the the USB does).

I don’t understand all the suggestions above (particularly “masterbrowser”) but let’s leave it, as it’s now working… :slight_smile:

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Hi @Ludwig,

Thanks for the update here.
If you run into any other issues, do let us know!

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