I recently upgraded my EISY to v6.0 and the update seemed to go smoothly, however since updating I keep getting communication error messages. Sometimes the devices will work fine and then other times I receive error message cannot communicate with that same device. There are times when the UD Mobile app seems extremely slow to respond as well. I have tried several times to revert back to the 5.8 backup I completed just before upgrading to v6.0 but this has not worked. Also I have tested/reset/restored my PLM and this has not seemed to work consistently.

Any advice on how to revert back to 5.9 (I'm not even sure this is possible) OR assistance with addressing communication errors would be great!

Reverting back to 5.8 is a complicated process and you shouldn't need to go that route. 6.0 is a stable release and superior to the previous. Not knowing what steps you've taken to revert back makes it difficult to offer suggestiions, and you may have made things worse.

In the Admin Console, If you click on Help | About, what is your current firmware an UI version?

After the update did you clear your java cache, checking all 4 boxes, and then download the Iox launcher from here:

https://isy.universal-devices.com/start.jnlp