If the ping returns an IPv6 address, the [System.Net.DNS]::GetHostEntry function fails as reverse lookup isn’t supported. This means that some clients cannot be managed. A simple test to see if the ping returns an IPv6 address could avoid this. I could do this but the function Test-ConnectionDNS is duplicated all over the place. 
Thanks for the feedback. Microsoft DNS does support IPv6 reverse lookup zones, it just needs to be configured. See this page for details: https://technet.microsoft.com/en-us/library/cc816876(v=ws.10).aspx
I just checked and you are correct about the Test-ConnectionDNS function being duplicated in multiple places. We will look into simplifying this in the future. In the mean time, you can continue to use the 2.1 version of the free tools if you are unable to enable DNS reverse lookups for IPv6 in your environment. Alternatively, you could look into the Recast Enterprise Tools as they have the option to disable DNS reverse lookups globally.
Thanks for the quick response. I personally cannot enable IPv6 reverse lookup, I’ll talk to super-administrators about that 
Might revert back to 2.1 in the meantime.
BTW thanks for these tools. They are very useful. Even though I have been using them for a while, viewing the videos yesterday on the wiki showed me things I hadn’t discovered.
I’ll look into the Recast Tools.
You are welcome and thank you for the feedback. There is a webinar next week if you are interested. Here is a link to the registration page https://attendee.gotowebinar.com/register/8127215383385849858