Null Data and Wireless

I prefer to look at it as 4 and 7 out of 8642 going missing.
With a direct serial wired connection, I would expect exactly 100% success. Anything less I would attribute to a failure at the receiving end to receive and process the data properly. As for Wi-Fi, as I wrote I have no experience. However, I was a little surprised by your figure of up to 1% failures - I was under the impression that Wi-Fi should be better than this. It doesn’t necessarily mean that the data didn’t arrive - it might have arrived late (because of other traffic on your LAN) and missed its slot, so a NULL value was recorded. And then of course if the next packet of data arrived on time, it would overwrite the late packet.

One way you might be able to investigate this would be to set up an EmonCMS Variable Interval Timeseries feed - probably recording the message count. This records the actual time of arrival in emonCMS of the message, and it would be apparent just where the NULL values were in relation to the time. You probably need to find one of my many explanations (in the forum) of how the Fixed Interval Timeseries works to understand what’s going on.

. For the record, which Wi-Fi add-on board do you have?