Tl-wdr7660 English Firmware Guide

Often, yes. The TL-WDR7661 is a variant with a different external antenna design. However, always verify hardware version numbers (v1, v2, etc.) before cross-flashing.

Version 4.0 is tricky. Try Archer A6 v4.0 US firmware. If that fails, OpenWrt is your only path. Check OpenWrt forums for "Realtek RTL8197F" support. tl-wdr7660 english firmware

Introduction: The Challenge of Regional Firmware Often, yes