Yes,

It does not work. Additionally, the ubiquity switch does not sync with 10gbit/s to one of the qnap switches (I tested with different cables and ports, but the led on the qnap stays orange, indicating connection speed lower than 10gbit/s)

As I’m maybe returning the switch due to the problems I hesitate to register it to access settings. Jumbo frames settings could actually be the solution. But with the problem mentioned in the first paragraph I’m not sure. A 300€ device should just work IMHO…

Thanks for the suggestion with ping, I will test it.