If my ISP couldn't provide a public IP. I will not be a masternode, right?
I found this error from start masternode.
"Not capable masternode: Can't detect valid external address. Please consider using the externalip configuration option if problem persists. Make sure to use IPv4 address only."
I had the same problem. Try to check under settings->options->network the "Map port using UPnP" option.
Also in your router enable UPnP
This solved my problem!
Thanks, but it still couldn't start after all checked