Hardware problems

I have a new computer, a tabletop PC I built myself. I was surprised it started the first time and everything seemed to be ok, but then Windows 10 failed connecting internet. The problem seems to be Realtek's LAN and/or Windows. Obviously I tried to find a solution, but nothing seems to fix it. Reading other people's experiences I'm also going to try a LAN card which is going to have Intel's chip. In fact my current PC has Intel's LAN and I never had problems with it.

This is one of those strange things about PCs and hardware. How hard it would be for OS to figure out what exactly is wrong? Windows 10 doesn't really help that much, it just says the driver is not installed. When I install the driver from motherboard's site it doesn't do anything and the driver installation software is giving another error which tells it's not connected. It is and the cable works in my older computer. Maybe the cable or router is too old? No. It can't be. We'll find out about that when the card arrives in couple of days.

I'm really bad at working with hardware. I just want the computer to say it's ok. I spent a lot of time learning about new PC hardware just to be able to select proper parts that fit together. I don't know about the motherboard, it sure does look like it was not the best one to have (Asus Prime H370 Plus). Then again when you build from generic parts it's easier to change them. I even got a retail Windows 10 which means it's not tied to the motherboard (oem) so I can in theory change everything.

I also hate the way internet is full of "information" about how to fix these problems, because in most cases it's just noise. It's so hard to find actual solutions. I think the best one I've read this far was to remove memory and install it to another slot. You know, to fix that LAN port. I think the companies who build this crap should give us confirmed user stories how these have been fixed, but it's not likely, because companies like Realtek are way too large to have any kind of connection to regular computer users. I don't even want to talk about my bad experiences with computer repair, it's just not worth it to send a defected motherboard to repair. You have to remove it and wait for several weeks for it to come back with a note that it works.