Sequoia suffers from a bug in the new feature “Local Network” which is a facility to allow or deny access to other devices on your network by an application.
This is enabled (with your permission) when first opening Roon after installing Sequoia however after a reboot or sleep or associated internal network conflict, macOS “forgets” the setting (even though the toggle is set to “on” in system settings/privacy & security/local network) and denies access. Toggling this off and back on, for all Roon entries, normally restarts a working link to the endpoints if you are having issues with the Eversolo disappearing.
I would try toggling off and on Roon access in System Settings/Privacy&Security/Local Network which should bring back the Eversolo. If this does work then your options to resolve the issue permanently are limited whilst waiting on an Apple fix (I am running 15.1 release candidate at the moment which will be released on Monday 28th but it still remains unfixed).
If you have a fair degree of computer literacy I would downgrade to macOS sonoma 14.6.1 or 14.7 but this involves a wipe of your system and rebuilding from scratch so do not do it unless you are totally confident in rebuilding your system, you can get the latest versions of macOS releases from Apple’s software download servers via the terminal or (easier) use a website like MrMacintosh.com which has links to the Apple download servers and instructions on doing this.