I need a combined 2.5Gbit + 10Gbit switch like the ^CRS310-8G+2S+IN^ but significant better.

- same size
- NO FANS (actual device with fans is an absolute NO GO!)
- proper cooling with COOL-elements on tot of the 10G cases !! (very strange that that cooling is missing!)
- at least 12 2.5Gbit ports (better 16)
- at leased two 10G SFP+ ports (to use it as an 2,5G only switch, next to a 10G switch)
- or better with eight 10G SFP+ ports to use it as a switch capable of managing both my 10G and my 2.5 G-network
- at least usable as powerful managed switch.
- reasonable price which will of course be a bit above the actual CRS310

I really really would like such a switch

PS four POE ports would be a welcome bonus

I think squeezing all that in and have it passively cooled to boot is going to be a tall order. Especially if you want PoE to boot. I wouldn't count on something like that appearing any time soon.

Fanless cooling with decent cool block on the switch chip and on the SFP+ cases, would just be proper thermal design. The sfp+ modules need at least as much cooling as the switch chip! Nothing more than that!
Twelve in state eight 2.5 ports seems possible to me as well. Also at this moment in time.

Note that I used to have a CRS317 with the same bad thermal design. Noisy fans cooling ^nothing^. The cpu cool block, was not cooled by the fans, and the SPF+ modules also not. So also not. So lots of improvement options in regard to thermal designs