MBP shuts off IP/TB when the lid is closed

[Kentzo]

I’m repurposing my old Intel MBP (15” 2016, first gen with touchbar) as a headless server. The plan is to turn off WiFi, BT and connect to my M1 Pro MBP using IP over Thunderbolt and Internet Sharing.

However, I’m facing an odd issue when the Intel shuts off the IP/TB shortly after (~30s) its lid is closed. In the Network pref pane On the M1 the Thunderbolt Bridge interface is shown as disconnected with the red icon.

Both MBPs are connected to AC and run the most recent Monterey. I am using a certified TB3 cable, system information on both MBPs report the connection appropriately (when it is working)

I tried sending the Wake on LAN packet from the M1 to Intel using the Mac address of the Bridge on Intel to no avail. Sniffing the Bridge interface on M1 shows ARP and mDNS requests originating from the M1 but complete silence from the Intel.

Is there a setting that I’m missing?

 

[chrfr]

Without a display and external keyboard/mouse attached, the computer will go to sleep when you close it, which is completely normal and expected behavior in a Mac portable computer. You could try the app Amphetamine to keep the computer awake when it's closed.

 

[Kentzo]

Without a display and external keyboard/mouse attached, the computer will go to sleep when you close it, which is completely normal and expected behavior in a Mac portable computer. You could try the app Amphetamine to keep the computer awake when it's closed.

I did not run a long thorough test, but with “wake for network access” power setting on it does not seem to become unaccessible when connected to the network with WiFi.