Whmcs and SolusVM installation help request

You need to check out your virtual lan settings, most likely it is deny all instead of allow vms or allow all. You also may want to use the proper ip address for the instance rather than local host or 127.0.0.1. Also feel free to ask solus support team, they have ben very helpful with some installation issues due to some bug in their script before. If you have a trial license you are still entitled for free support.