Issue with Yealink T4X & T5X Series Devices - Firmware

We are tracking issues with some partners / customers with Yealink T5X Series Devices and Firmware / Device Boot Loop. Yealink made changes to their firmware between v85 - v86.18 that is causing firmware corruption issues when moving between certain firmware versions. Please do not adjust provisioning settings in regards to firmware versions until we have had some time to install some programmatic safety barriers to prevent firmware update attempts on these series devices.

We have determined that in addition to Yealink T5X running 96.86.0.X models some T4X models using the 66.85.0.X firmware are affected. We are working to make programmatic coding changes on our Management and Device Provisioning systems to put logical safety blocks in place to prevent devices from automatically attempting to update firmware based on Yealink's systems and then create boot loops for phones unexpectedly