To fix the Yellow exclamation mark in Device Manager, you must ensure that the respective device drivers are installed on your system. Been googling thought maybe related to Win 1903 but just had it happen on a Win 7 machine. Red X usually means there is no physical connection - cable unplugged, switch down, no network driver loaded, etc. This tutorial covers all Step By Step process how to fix this problem. This problem generally occurs due to Wi-Fi Router connected to Pc. My HP all-in-one PC crashed and has now been repaired and Windows 7 has been reinstaled, but it is not connecting to wireless internet. (Code 28) There is no driver.