Sorry, your license key isn't valid for this domain – domain is IP restricted

We're testing Perch out as a potential solution to power a wiki. I envision this might be upgraded to Perch Runway in the near future. However, we've hit a stumbling block.

I've put the domain in as one of the authorised domains. However, when visiting the site and attempting to login, I'm getting the "Sorry, your license key isn't valid for this domain" error.

Now this domain is private and as such, it has access restricted by IP address. Is this this likely to be what is causing the issue and if it is, what is the workaround for this?

Thanks in advance.