One of out esxi host "PowerEdge R730" running on 6.7 U3 and we upgraded it to 7.0 U3K build with dell custom ISO and post upgrade it lost the connectivity to management and production network.
Any suggestion how to fix this issue.
Lost the connectivity means , it is showing not responding in cluster ?
Are you able to ping host from vcenter server and vice versa
what is status of hostd service
Probably related to drivers and your physical nics not being recognised by the Dell image.
Check out these posts: ESXi 7 fails - "No Network adapters detected" - VMware Technology Network VMTN
Update your drivers.
From experience, I always have a back door managment interface on hosts using a std vswitch and a 1Gb nic as I don't always trust a vDistributed switch and uplinks.
Broadcom network adaptor were not showing inside the host and there was no connectivity with the VC as well.
It seems drivers problem plz check compatibility
https://www.vmware.com/resources/compatibility/detail.php?deviceCategory=io&productid=12109&vcl=true
or
You can open case with support