I installed a fresh copy of PxPlus 15.10 using the .zip file. The ADDR didn't error, but opening the tcp port using a tim= value still did. I ran the original PxPlus installation by launching the pxplus.exe external to our application, meaning no custom startup. When I did that, the ADDR didn't error either. So I believe the original installation is good, but maybe our custom start up sets certain parameters that impact the behavior of ADDR.
After reading the recent posts from you and Chris, I tried the ini IPV4ONLY=1 setting, and that also worked for me. Here's what's confusing though. The issue only occurs when using a tim= value on the open. Why does it only fail when using a tim= value on the open? Is this a windows issue or a PxPlus issue?