1. You probably have about 15 drivers that need to installed after a fresh install.... a link will get you to one of them
2. A Realtech LAN chipset would be very unusual; Intel is most common these days. Are you interested in wasting your time installing drivers for hardware you don't have ?... or are you interested in installing drivers for hardware you actually do have ? I think a solution that works and takes a few extra minutes is a better alternative than one which can be done quickly but in the end, must be undone because it's not appropriate for your system.
3. Where did you get this PC ? Is it a mass market pre-built system ? If so, say Dell ABC-700, then you just go to the Dell web site, find the model number and download the appropriate drivers.
4. However, if you got this mish-mash of old and new drivers installed, then 1st step would be to get rid of all the old drivers which may interfere. A fresh install is the best way to do that if wrong drivers have been installed.
5. If you do install just the LAN driver, go on and let Windows Update install your hardware drivers, then your system is likely to be more messed up than it is now.
6. If you'd spend a bit more time in preparation and data collection, in the end you will save hours of your time.