Good afternoon,

I’ve been having issues with my m1exp unit. I’ve owned the unit since 2011 and up until the last couple weeks the unit has been randomly disconnecting. I usually power cycle it and it comes back online, but as of late last night it is not ping able. I use my router to issue the m1exp a static ip. I’ve changed Ethernet cables, tried different switch ports, rebooted my router and switch, turned off my Isy 994i and home assistant, put a jumper on the pins to force a static ip and then back to a dynamic ip. Read multiple troubleshooting threads pertaining to the issue but the device won’t go online. Any assistance is appreciated.
Usually, using the jumper method to reset it seems to fix it for me.

It's also possible your power supply went bad (although not that common if you're using the OEM supply). Is your status light blinking? If so, what's the sequence?
Actually, the PS seems ok. The light remains solid. I got it working last night. One of the problems I think I'm having is I use both Home Assistant and an ISY with both using ELK interfaces. I know the ISY connects to the ELK via port 2101 (non secure) and I think Home Assistant uses 2601 (secure) port. I would think that since both services use different ports there wouldn't be a conflict. As of now, I disabled the Home Assistant portion and will continue to monitor if any issues arise.
I know you can have multiple connections to the insecure port (I do this myself), so you could switch HA to the insecure port as well.
Hmmm that's good to know that I can setup HA on the non secure port. I let HA auto discover Elk and perhaps I can use the manual settings to force it to use the non secure port. It seems when I have the HA elk integration running, I see problems.

From the ELK M1 integration setup:

The address string must be in the form 'address[:port]' for 'secure' and 'non-secure'. Example: ''. The port is optional and defaults to 2101 for 'non-secure' and 2601 for 'secure'. For the serial protocol, the address must be in the form 'tty[:baud]'. Example: '/dev/ttyS1'. The baud is optional and defaults to 115200.

So that should work. I did limit it to just inputs/outputs/zones I care about, both for performance and management purposes. If you're monitoring everything, especially over the secure port, I could see how that may cause some issues.
I’ve been monitoring the M1EXP for the last 3 weeks and it has been working ok until a couple days ago when it stopped communicating with HA and the ISY. Now the device has the blinking orange power light. I checked the power supply and I’m getting 12VDC. I’m thinking at this point the unit might be defective.
Keep in mind that measuring 12VDC doesn't mean the power supply is good. I've had plenty which report fine, it's once you put a load on them that devices started acting sketchy. If you have another power source, give that a shot.

Are you still using the secure port, or did you switch it? If it's only happening with HA connected, it might just be a software bug on the M1XEP side. I do remember the Elk M1 HA component being updated in the last few months.

Of course it's possible the M1XEP just went bad (I've had that happen due to a power surge), but since these are so hard to find, I'd keep trying to troubleshoot this.
I did switch to a nonsecure port. I now have everything disconnected from the M1EXP. You're right that the unit is difficult to find. I'm going to order a new PS and hope for the best.