I have an 8-port MS220 connected to an MR18 powered by POE and am experiencing the same things you have described for the past week.   I updated everything last weekend and had good service for about a week, but had more issues this morning.   The logs show the STP message that you shared.   It seems very strange that Meraki isn't able to identify the issue.      I only have the single MR18 POE device on my MS220.   Other devices are one dedicated wired ports.   This is my home network.      Please let me know if any resolution is identified.     Thank you ... View more