Yes, my router is a Swisscom Internet box (1Gb/s). It worked straight away.

I read in the Unifi forums that there are problems with 2.5 Gb/s with third-party products. But maybe this has already been solved. Ubiquiti has worked very hard on the software quality of the Unifi product group in the last 1-2 years (and is still working on it).

Hope this helps.