Vibration/Humming Noise 1500-1900 RPM

Hello everyone.

I've searched everything again, but unfortunately, I'm still not any wiser.
My ARL engine, with 177,000 km on the odometer, starts with a strong knocking/vibration in gears 5/6 at an RPM range of 1500-1900.
In the lower gears, the engine speed range is traversed more quickly, which is why this phenomenon is less pronounced.
In this case, the interior rearview mirror vibrates so strongly that it becomes impossible to see anything.

Having encountered information about ZMS/engine mounts here, I would like to know to what extent this error pattern might apply to my situation. Also, what is your assessment of the likelihood that these components are defective?

Other issues such as clutch slippage or annoying noises do not occur.
'Errors are both cold and present. Error codes are not stored.'

Thank you in advance.
Sure, here is the translation of the text from German to English:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which means 'Sincerely' or 'Best regards' in English.

ZMS, engine mount, or tuning with excessive torque.

Best regards, Rainer.

You're welcome for the information. I'll be replacing the timing belt during the major inspection, and I'll also replace the engine mounts at the same time.
I will choose ZMS if things don't improve.

The engine is largely in its original condition (no modifications).

I will keep you updated.

Hello,

Quote:

there's a strong booming/vibration

in the hallways 5/6.
It feels like the problem lies in the rubber bushings, such as those in the control arms, strut mounts, engine carrier, engine mounts, and the lower engine support.
At lower temperatures, they become slightly harder, which results in a different sound profile compared to when they are very hot.