Vatoe

Okay that took a minute for me to reply, as while I was waiting for your last reply, I did try the new config option and the issue did re occurred with cache pool - unmountable. On this occasion however, the SSD was fine, being mountable. I then re-installed a backup copy of the flash drive (forgetting to get the diagnostics) and re did all the processes remove pool etc so as to get the a fresh copy of the diag's when the issue occurred again. However, this time I stopped the docker service before I restarted the array (essentially to save time if I was constantly starting a stopping the array) before restarting the array and to my supprise the cache pool came back online! I then stopped and restarted the array, restarting the the docker service in between and once again the cache pool came back online.

Weirdly never had an issue with the SSD being unmountable, like I did yesterday, it was fine all occasions.

So if this happens to anyone else and is reading this in the future, you may want to try stopping the docker service prior to restarting the array, get the cache pool online first, stop the array, restart the array and should be up and running. I don't think it was a co-incidence as I stated I did the have the unmountable issue on the previous try with the docker service being stopped.

Jorge, thanks for all your help!

I have answered my own question, and will leave the process here in case anyone needs to accomplish something similar in the future.
 
 
In essence, I shut down the server (after moving the data of the disks I was removing via unbalance), remove the disks, replaced two with the new ones (18TB's) and restarted. I then did the 'new config process' (found in tools tab) on the array part only. I checked to save my pool devices. Then back to main tab and reallocated the data disks (included the new one 18tb) to their slots. I left the parity for the moment as I knew I had to format the new data disk. Started the formatting of the new data disk by starting the array. Once formatted, shut down the array and added the (new 18TB) parity disk, which kicked of parity process on restarting the array. The data on remaining disks were untouched. Once the parity is complete, I plan to move some data onto the new data drive using unbalance.

Okay, I have managed to fix this issue. Anyone who has this issue this should help.
 
1. Make a current backup of your flash drive (for the just in case scenario)
2. In unraid console remove the docker network database :  rm /var/lib/docker/network/files/local-kv.db
3. Then restart the docker network:   /etc/rc.d/rc.docker restart
After the restart br0 should now point to ipvlan. I am once again able to use a fixed ip address on br0 network for docker containers.
Thanks to bmartino1 for chimming in.
 
edit: you will need to re-create any custom networks and get your docker containers pointing to the relevant recreated networks. Some of my docker containers didnt restart so I had to reinstall the container with the 'newly' recreated network.
 
 

Not sure how as I tried many things, but my issue seems to be resolved. I now suspect that my problems revolved around my internet service connecting out to the Community App store, not an unraid configuration issue.