I logged the Printer connections after factory resetting the Printer and putting it in LAN Mode.
If you say LAN Mode… or Offline, Why does the Printer requests DNS and reaches out to external Time Servers
If you claim Offline mode, you should stand on that.
The Printer does not respect DHCP Options for NTP Servers. Why?
Can you also add what firmware version the printer is running? Interpreting LAN Mode as “offline” is dicey at best (since it does not say that). Probably should consider it more simply “not Bambu Cloud connected”… as I bet it also still does firmware update checks.
P1S FW 01.07.00.00 (edited above)
And they say, “you can use your printer offline in LAN mode”
despite that - if you implement your dhcp client correctly, you respect dhcp option 4.
you can implement an standard ntp server, if none is provided - and for time sensitive devices this is advices. But if option 4 is present, you don’t get to ignore it.
Edit mightn’t have got saved, as not seeing any signs of it.
Yeah, something seems a bit odd with the LAN mode, as I’ve seen mention from others that they can’t connect to the printer in LAN mode, but then others say they can, so all seems a bit fishy/fussy… especially if you go back to how it is worded… like “offline” is not actually mentioned anywhere here… just that the cloud remote monitoring/control capabilities and print history won’t be available… there is mention that X1 can do local “AI” if not connected to the internet… but nothing for the P1 series.
This might be of interest also…
It still stands true, you can disconnect it from the internet and it will function. It’s time will probably get skewed though 
Given what you noticed and what @pfeerick linked, you can be certain they hard coded NTP servers in their configuration for the ESP32. Not sure why they went that route, but if I were you, I’d put in a feature request to update the firmware to support using DHCP options.
Also, I suggest using option 42, as that’s the correct one for setting NTP. I suppose you can set both, but 42 is the right option.
Seeing the same thing.
For the moment, NTP only.
The printer does NOT obey NTP from DHCP.
The port might be for NTP, but who knows at this point. The endpoint could be anything.
Is the NTP in your DHCP specified as an IP address or FQDN?
I did not probe my DNS server - but the Servers are AWS, Microsoft (not Azure, for some reason) and a local cloud hoster in my area.
according to the Pcap I did, it is just NTP.
DHCP Option 4 needs to be specified as IP Address(es), so providing the Option 4 as FQDN would be invalid.
Oh - it never saw any internet.
You can just DNAT the Request to your local NTP Server - why would I want any other Time Provider than the one I already have across my whole infrastructure.
The NTP is in IP format. <Some more characters for 25 min.>
