One AC mini HW1 and firmware 3.6.0 or greater

currently i am running firmware 3.5.4, and all my clients can connect with no issues, but as soon as i update to 3.6.x (including the 3.6.2 beta), some of my clients say they are connected and show on my Balance One Core as having an IP, but i can not connect to them, ping them etc. it not all of my client only some of my IoT devices,

Does any one have ny ideas why ?