Seems like this would be better solved by incorporating the MyOpenHAB Cloud components into the server itself, and using Dynamic DNS to access it instead. Seems like it would be simpler, and cheaper, than building my own server in the cloud.
That would likely technically make that a server, usually violating the terms of service for many residential Internet services.
I tried free IFTTT a couple of times and was lucky of a job automatically ran withing 24 hours of triggering. I was using webhooks and email for testing. I do not understand the usefulness.
Well, technically, myopenhab.org accessing the local openhab install makes it a server anyway, as would accessing anything at home while outside of it. ISPs only really care about volume, and serving it up for personal use is definitely an arguable grey area.
IFTTT was working for me when I originally set this up, changes were applied within a minute. Granted, the Arlo integration is pretty weak, as it can only change the mode for an entire Arlo hub (which is why I bought a second hub for the outside vs. inside cameras).