Are you by chance using M1XEP firmware 1.3.28? I had (and actually still have) a similar problem where my M1G would making a clicking sound once a minute, and then the M1XEP would reload its configuration. During the reload time (which takes 10 seconds), the M1XEP is unwilling to talk to anything.
I have the insecure port enabled to allow CQC and my ISY99i to talk to the M1XEP, so I was also able to use:
telnet ###.###.###.### 2101
to open a connection, and when I do, the click is accompanied by
08RP020034
and then ten seconds later I get
08RP000036
06IE00AC
and things are good for 50 more seconds.
I spoke with Elk extensively about my problem. For whatever reason, the only way I am able to resolve it is to go back to the 1.3.26 firmware, which is rock solid for me.
I hope to learn why some day, but in the interim, I'm just happy to have things working reliably.
I avoided downgrading my M1XEP firmware for two months due to the warning pinned in this forum about doing just that. However, Brad at Elk told me I coudl safely move backwards as long as I stayed within the 1.3.* releases, and I was desperate to restore functionality, so this is what I tried, and it is what worked.
In case anyone wonders, I also tried moving back to 1.3.28 after the downgrade, which brought the problem back, and then downgraded back to 1.3.26 again, which restore everything.
Chris