Problem: I have 2026 MB GLC300 and I can’t reset maintenance light with Topdon Phoenix Smart diagnostic scanner. I set up everything as the image show in the scanner, and in the end of the process the scanner shows Ethernet connection or control unit coding, any ideas?
Ethernet cable, internet and head unit are perfect.

Solution:

It is a 2026 vehicle and requires gateway unlocking. For vehicles equipped with security gateway, the software will normally display a prompt like the one shown below.

That will require either autoauth and an approved scan tool (Topdon devices currently do not support unlocking the Mercedes gateway yet) OR Mercedes j2534 software and the RLink lite or RLink j2534.