Here is the direct and official firmware link for the (often labeled as US/EU/Global version), along with a step-by-step guide to find and install it safely.
To update the firmware on your TP-Link Archer C6 V3.20, follow these steps: tp link archer c6 v320 firmware link
The following are regional download pages specifically for the Archer C6 V3.20 hardware version: TP-Link Baltic Support TP-Link Archer C6 v3
Optimized system restart, added by default for iOS 14 security, and added OneMesh support. Archer C6(EU)_V3.2_210513 Primarily focused on optimizing wireless performance. Community Beta/Hotfix Security patches: Critical if you use TP-Link Cloud