Noise from the gearbox – only in the 1./3./5. gear

Please for help!! The 2.2 liter diesel, 116Ps are produced in the 1st/3rd/5th gear while driving sounds like a tramway. It sounds a bit grinding howling… in the 2nd gear it’s not much to hear in the 4th gear at all!! The friendly dealer knows nothing without intensive search right away. Does anyone have ideas where the problem might lie??