I sysupgraded my Meraki MX60W from OpenWrt 18.06-SNAPSHOT r6917-8948a78 to 6984-fa0275b. After rebooting, I could not access my device's opened ports as before. Driving miles to the router, I'm able to login to LuCI and SSH. I can ping the Internet from the router; but the LAN does not have Internet connectivity.
Also, r6917-8948a78 appears to be responding extremely slowly (pages in LuCI load slowly, scripts loaded slowly, etc.) ...in addition, I noticed a very odd thing...tcpdump was installed after flashing, was it added to the new images??? It only existed in flash prior to sysupgrade...perhaps, somehow the partition wasn't wiped...?
I reverted back to r6917-8948a78 to resolve my issues at this time.
FYI, I flashed a fresh Meraki MX60W with the same BIN and TAR files, no issues...
EDIT: The new Meraki I flashed is also having issues on 6984-fa0275b that renders it inaccessible and therefore, unconfigurable. Upon subsequent boots, you cannot access it; but LAN to WAN worked: