I have been having the same problem with Realtek not detected but noticed that when I put the laptop to sleep and wake it up again, the Realtek icon appears.
It has been working for the past few months but during my recent trip away to another country, the network adapter failed. A code 12 error message popped up and I wasn't able to connect to the internet through cable anymore, though my wireless is still working.
Service support from Samsung was requested for twice on the same matter, one during the first encounter and another when the error Code 12 appeared. The first time after noticing that waking up the laptop activated Realtek, I have not visited the manufacturer for the problem as it seems to be working alright after that. Second time though, Samsung tech service deleted Realtek from my laptop and said he couldn't help but advised me to visit their manufacturer.
Now I ended up not having a Realtek on my laptop and can only use wireless network to connect to the internet.
I need help on this as haven't been able to find any useful topic on any forum about how to solve this problem.
I am using Samsung Series 5 laptop.