I know this is an old post, but I recently was having this same issue. After reading this, I changed my mask from /24 to /28 and all is well. Not sure if it is a bug or what, but that seemed to help me (since I am only allowing 10 concurrent connections). I am on Version 2.4.4-RELEASE-p3 (amd64), UDP on IPv4, Remote Access(SSL/TLS), port 1194, built via wizard. Thanks.