Hi, @Dominik_2 I'm a little late here but I'm having the same issue. Did you ever figure this out? I can't even get a 2019 Mac Pro to properly activate LOM and a 2023 Mac mini which gives me the same "Address Already In Use" error. Here's all my testing and info. Apple are you there??? Infrastructure: • Mac mini 2023 (M2, 10Gb Ethernet, "MacMini.local", macOS 15.x Sequoia 15.7.4) — MicroMDM v1.13.1 • Mac Pro 2019 (MacPro7,1, Intel T2, "MacPro.local", macOS 15.x Sequoia 15.7.5, T2 firmware 23P3120) • Both supervised via Automated Device Enrollment (DEP) through Apple Business Manager • Both enrolled: IsSupervised = 1, APNs working on both • Both are Controllers and Clients LOM Current State: Mac mini (Apple Silicon M2): • LOM profile installed ✓ • lom0 interface active ✓ • Port 55555 listening on * ✓ • LOMDeviceServerColsolidated path (Apple Silicon) ✓ • com.apple.AppleLOM.XPC active=1 ✓ • com.apple.AppleLOM.Watchdog active=1 ✓ • Mac Pro CAN reach mini's lom0 port 55555 — TCP connection established ✓ • BUT connection immediately fails with "Address already in use" ✗ • SMC watchdog heartbeat NOT appearing in logs ✗ • LOMDeviceClientLocal setupXPCConnection Connection error Connection invalid on every profile push ✗ Mac Pro (T2): • LOM profile installed ✓ • LOMDeviceServerLocal path (T2) ✓ • T2 communicates via en7, bytes exchanged (261/5397) ✓ • LOMDeviceClientRemote install result: Success ✓ • com.apple.AppleLOM.XPC active=1 ✓ • com.apple.AppleLOM.Watchdog active=0 ✗ — never checks in • Port 55555 NOT listening ✗ • PrimaryIPv6AddressList always empty ✗ • en0 goes completely dark when Mac Pro powered off ✗ "Address already in use" — Known Bug Since 2022 - from your post Watchdog endpoint is the key difference: • Mac mini: com.apple.AppleLOM.Watchdog active=1 → LOM fully initialized • Mac Pro: com.apple.AppleLOM.Watchdog active=0 → LOM never fully initializes • The Watchdog has HideUntilCheckIn in the launchd plist — the process must explicitly check in with launchd to activate it. T2 firmware never does this checkin, so Watchdog stays inactive, SMC heartbeat never fires. Mac Pro DID reach mini's lom0 — but "Address already in use": LOMControllerConnection [Port: 55555] acceptConnection New Connection C1 fe80::XXX%lom0.49438 tcp local: fe80::XXX%lom0.55555 Connection State Changed 4 error: Address already in use The TCP connection IS reaching lom0 and being accepted. But TLS setup immediately fails with "Address already in use". nc -6 -zv ::1 55555 succeeds on mini — port 55555 accepts connections via loopback ✓ lom0 open files comparison: Mac mini lightsoutmanagementd has: • *:55555 listening ✓ • Multiple user-packet-pool entries ✓ Mac Pro lightsoutmanagementd has: • NO port 55555 • NO packet pools • Much simpler file list — T2 path is far less initialized Periodic usymptomsd errors on mini — lightsoutmanagementd trying to connect to com.apple.usymptomsd failing with error 159. Only appeared twice since reboot this morning — NOT the regular heartbeat. We previously DID see frequent SMC watchdog heartbeats on the mini (every ~60 seconds) before ‘something’ corrupted the daemon state. Those heartbeats have not returned since. LOMDeviceClientLocal Connection Invalid — Despite com.apple.AppleLOM.XPC being registered and active=1, LOMXPCService connects via mach=true and gets Connection Invalid every time. The mach=false path (profile install) works fine. The mach=true path (SMC/NIC activation) fails. The "Address already in use" Mystery: When Mac Pro connects to mini's lom0 port 55555, the connection is accepted but immediately cancelled with "Address already in use".