the last firmware update was about 3 weeks ago: https://community.smartthings.com/t/aeotec-smart-home-hub-2018-2015-model-hub-firmware-release-notes-0-52-21/280496
There have been some users reporting z-wave offline issue since March 14th: https://community.smartthings.com/t/most-z-wave-devices-stopped-responding-please-help-14-march-2024/279703/
which model hub do you have and what is the firmware version? Is the hub online? Are non z-wave devices online and working? Can you identify some of the devices (brand/model) you are attempting to exclude/pair again? Have you tried excluding from the Advanced Web App?