You need to specify the correct domain name instead of "etcvpqlc101" for the endpoint. The domain name will end in .com or .org etc. Note that may not solve your problem because I think that webhook is going to require you to authenticate to HP and I don't know how their API is structured.
That looks to be a private domain. The computers behind your company firewall cannot receive inbound communication from computers outside the firewall. Remember, that Quickbase is sending this from a public server.
To trigger a workflow inside your firewall, consider using a different communication protocol, one that is allowed to be sent inbound through a firewall. Email protocols can do this. Your computer can receive an email from outside the firewall (although indirectly).
A simple solution, therefore, is to have Quickbase instead send an email notification to a Service Account mail recipient. On receipt of that email, you can run a script that will grab the required information from Quickbase.