There were issues with these on-board nics
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02)
Subsystem: Giga-byte Technology GA-EP45-DS5 Motherboard
But they have been fixed in recent kernels. All of the RTL8111/8168B's have had one issue or another over the years. The rev01's were quickly fixed, the rev02's went ~1.5 years without a fix. It's all good now
I have another system with Realtek Audio ALC889A, has worked out of the box for as long as I've owned it.