obsidian-vault/300 areas/360 Dev-Ops Network Computers/Error Tracking.md

created, modified, title, summary, type, client, project, status, priority

created	modified	title	summary	type	client	project	status	priority
2026-09-06	2026-09-06	Error Tracking	Log of network/system errors encountered and their fixes	note	sam	devops	active	5

Error Tracking

A running log of errors encountered across the network, with root causes and fixes. Append new entries as they occur.

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2026-09-06 — Router: "Another management entity is configuring the Broadband Router"

Symptom

While in the router admin (192.168.20.1), saw:

Broadband Router Error — Another management entity is currently configuring the Broadband Router. Please close the Broadband Router Configuration window, and try again in a few minutes.

Error appeared repeatedly; also coincided with .13 losing all network connectivity (wired + Wi-Fi + Tailscale unreachable from .27).

Root cause

Not a second admin session and not a rogue device — .13's own flapping Wi-Fi adapter (wlp4s0) was seen by the router as a "management entity":

• .13 has two MACs / two IPs on the router table (root of the confusion):
  • Wired enp42s0 = MAC 34:5a:60:a4:cc:8c → 192.168.20.13 (LAN)
  • Wi-Fi wlp4s0 = MAC a0:f3:c1:d0:e3:2b → 192.168.20.46 (2.4G)
• Wi-Fi kept going DORMANT / re-registering and the default route flipped onto it → router interpreted the churn as a second configuring device.
• sudo reboot on .13 cleared it. Error has not returned since.

Verification / non-causes

• Router login log showed no login except .27 → no foreign admin session.
• Client table showed only known devices (ESP32s, Pis, .27/.35/.51/.13, etc.).
• Not caused by Langfuse/Clickhouse removal (unrelated; those never touch networking).

Potential fix — pin the Wi-Fi MAC address

If the error (or Wi-Fi flakiness on .13) recurs, the likely fix is to stop the Wi-Fi adapter's MAC churn:

• On .13, disable MAC address randomization in NetworkManager for wlp4s0, forcing a stable MAC so the router sees one consistent identity per interface:

  # /etc/NetworkManager/conf.d/ (or via home-manager)
  [connection]
  wifi.cloned-mac-address=permanent   # or "stable"
  # per-interface: wifi.mac-randomization-disabled
  

• On NixOS this is done in hardware-configuration.nix / networking options (e.g. networking.wireless or NetworkManager connection settings in home-manager), or simply disable the Wi-Fi interface entirely if wired is preferred: sudo nmcli radio wifi off.

Related notes

• .13 network layout: enp42s0 = wired .13, wlp4s0 = Wi-Fi .46 (2.4G). Default route prefers Wi-Fi (lower metric) — worth reviewing if flakiness returns.
• 192.168.80.0/20 bridge on .13 is normal Docker (wherewoof-db_default subnet) — not an issue.