Kindly be informed, that unfortunately, but the DYMO Label Software v.8. is incompatible with the new macOS 26 Tahoe. The software is officially obsolete, we do not develop it anymore. The last update for it was introduced when Apple released their macOS 11 Big Sur, it was in 2020. The printers you have, with the exception of LabelWriter 450, are incompatible with the current software.
LabelWriter Duo and LabelManager PnP Wireless are obsolete for some time now (keep in mind that LabelWriter Duo is a 20 years old printer) and there are no drivers for them in a our current DYMO Connect software.
LabelWriter 450 was still being manufactured when the DYMO Connect was released, therefore drivers for that model were and still are included in the software.
Those older models would be working on an older OS (up to macOS Sequoia) and on Windows PC. Once again, I am sorry for the inconvenience you are experiencing.
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Disclosure: I am the developer of Label LIVE.