What should be checked when experiencing transmission issues on an Audi A6?

I've been noticing some strange behavior in my Audi A6's transmission. It's not shifting smoothly and sometimes makes strange noises. What are some components I should check first to diagnose the issue?

First, make sure there is enough transmission fluid and that it is clean. Low or dirty fluid can cause shifting issues and strange noises.

Check the transmission filter for any clogs or debris. A dirty filter can also cause problems with shifting.

Inspect the transmission linkage and cables for any damage or wear. A faulty linkage can cause difficulties with shifting and can lead to further damage if not addressed.