The RTL8196E OpenWrt Guide: Breathing New Life into Legacy Hardware

Patch arch/mips/ralink/mt7620.c (or create rtl8196e.c):

Kernel Support: For years, it required a heavily patched, outdated kernel (often 2.6.x) provided by Realtek's proprietary SDK, making it incompatible with modern OpenWrt. The OpenWrt Conflict

Historical Ports: Older repositories, such as vido89/Open-Wrt-RTK and Alexey-Tsarev/openwrt-rtl819x, provide experimental builds based on older kernel versions (e.g., 2.6.x or 3.x) for specific devices like the TOTOLINK N601RT.

Developing for the Realtek RTL8196E on OpenWrt is complex because this SoC uses the Lexra architecture

Verdict: Use RTL8196E only for low-cost IoT gateways or learning embedded Linux. For production, switch to MediaTek MT7620/7628 or Qualcomm QCA9531 (both well supported in OpenWrt).