endpoint:80/sub is not recognized in grpcurl

[nptri]

Hi, I have a service endpoint as endpoint:80/subgrpc when I pass in whole grpcurl as this:

grpcurl -d '{body}' -H 'authorization: Bearer jwtKey'  -plaintext endpoint:80/subgrpc service/serviceName

return log as:

Failed to dial target host "endpoint:80/subgrpc": dial tcp: lookup tcp/80/serviceName: unknown port

Did I wrongly pass anything into the command ?