Updating the SWIS api port to 17774 has caused a 404 'Not Found' error with the Gosolar Go module.

You still will need to import the module as normal: 

import (
	"github.com/mrxinu/gosolar"
)

Then you will make a new instance of a SolarWinds Client:

func main() {
	hostname := "localhost"
	username := "admin"
	password := ""

	// NewClient creates a client that will handle the connection to SolarWinds
	// along with the timeout and HTTP conversation.
	client := gosolar.NewClient(hostname, username, password, true)
...
}

Here is where you make the major change. You need to set the "URL" value of the "client" variable to overwrite the 17778 port:

client.URL = fmt.Sprintf("https://%s:17774/SolarWinds/InformationService/v3/Json/", hostname)

Now the calls will connect successfully, granted you have them formatted correctly and the account you're using has the required access!