XU4 getting network but can't see on the network

[seawolfssn]

Brand new XU4, running the latest version of Ubuntu + MATE...
wrote the image last Thursday, planned to connect solely through wifi; connected screen and inputs and was able to get it on my network. I was able to see it on my network, ping it, ssh to it, vnc to it, RDP... etc.... then let it run headless for 3 straight days without any problems, through multiple reboots.

Then suddenly drops off the network. I re-write the image as i hadn't done anything yet, just testing. Figure something must have gone wrong.

Now, it gets an IP, and i can ping out and do whatever.

But when it boots i can only see it on the network for the first 3 seconds after it starts its network and then it goes dark. can't ping, can't ssh, can't do anything remotely. But as far as i can tell from the device itself, everything looks normal.

I haven't made any changes on my network and I'm using the exact same image that was working exactly as intended for 3 days.

Everything looks completely normal... but obviously not.

I am thoroughly confused.

[odroid]

Which Kernel version do you run? Is it 4.14.150-170?
Otherwise, update the system with the following steps.
https://wiki.odroid.com/odroid-xu4/os_i ... st-upgrade

Can you show us "syslog" and "dmesg" output when you meet the issue again?