This took me two days to figure out and I’m not entirely sure why it happened, but throwing it out there in case someone else runs into the same problem…
If you’re using a Mikrotik CRS as your switch, Synology NAS as your iSCSI drive, and you have jumbo frames enabled on the NAS, you may run into an issue where ESXi will not be able to connect to the iSCSI drive. You’ll be able to access the NAS via HTTP and everything else on it will work fine, just not iSCSI.
The fix? Turn off jumbo frames on the NAS. Why? Really good question. I’m only a little over a day into using the Mikrotik CRS, and I have a lot to learn still about it, but in the short term, this is how I got iSCSI working.
