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LG C5 wake-up on Lan fails to wake LG webOS displays in standby due to Unicast UDP destination instead of Layer 2 Broadcast #603

Description

@filipefumaux

When waking an LG webOS TV (e.g., C-series OLEDs / webOS 24+) from standby, ColorControl sends Wake-on-LAN (WOL) magic packets as unicast UDP datagrams targeted at the device's specific IP address (e.g., 10.10.50.96) rather than broadcasting across the subnet or to 255.255.255.255 (IPAddress.Broadcast) with EnableBroadcast = true.

When LG OLED TVs enter standby mode:

The webOS TCP/IP stack powers down completely.

The router/switch/access point's ARP table entry for the TV's IP address expires or becomes stale within 30–60 seconds.

Because the packet is addressed directly to the inactive IP, network switches and wireless access points drop the unicast frame instead of delivering it to the sleeping physical PHY.

Consequently, the TV never powers on, even though ColorControl logs WOL succeeded.

Environment

Application: ColorControl 11.0.0.0+

OS: Windows 11 Pro (x64)

Target Device: LG OLED48C56LA (webOS 25)

Network Layout: PC on Wired Ethernet (10.10.50.6) $\rightarrow$ Managed Router/AP $\rightarrow$ TV on Wi-Fi (10.10.50.96)

Log Analysis & Evidence

From LogFile.txt:

2026-08-28 18:50:37.1299|DEBUG|ColorControl.Shared.Services.WolService|Sending WOL packet to MAC-address xx-xx-xx-xx-4F-4A
2026-08-28 18:50:37.1452|DEBUG|ColorControl.Shared.Services.WolService|Broadcast WOL in network: Ethernet (Realtek Gaming 2.5GbE Family Controller), local address: 10.10.50.6, destination IP-address: 10.10.50.96
2026-08-28 18:50:37.1452|DEBUG|ColorControl.Services.LG.LgDevice|WOL succeeded
2026-08-28 18:50:37.6633|ERROR|LgTv.LgTvApiCoreCws|HandleMessage: status: Closed, exception: Empty response received. Assuming connection closed.
2026-08-28 18:50:37.7469|ERROR|ColorControl.Services.LG.LgDevice|Error while connecting to 10.10.50.96: Can't send message

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