1. RESET TO FACTORY DEFAULTS. DO NOT SKIP THIS STEP. 2. Flash the openwrt firmware like normal through the web interface. Obtain openwrt from here 3. After flashing, telnet into your router at 192.168.0.1 (some cases, it can be 192.168.1.1) 4. Install LUCI using the command "opkg update; opkg install luci" without the quotes 5. Run command "passwd root" without the quotes to set the root password. 6. Open your web browser to 192.168.0.1 (some cases, 192.168.1.1) and login using the root password you just set 7. Find firmware upgrade page (under system tab), and select factory-to-ddwrt.bin and uncheck Keep Settings 8. Flash image 9. Reboot the router after about 2 minutes (I'd wait more just to be safe!) 10. Open your browser to 192.168.1.1 and profit!
Flashing to factory stock from DD-WRT
1. Download stock firmware 131217 from here 2. Unzip the archive 3. (Assuming you are running on Linux/Mac) open terminal and cd to the directory where you extracted the firmware. 4. Run "dd if=ArcherC7v2_en_3_13_34_up_boot(131217).bin of=tplink.bin skip=257 bs=512" without the quotes, assuming you downloaded the linked firmware image. This should create a new file named "tplink.bin" THIS STEP IS IMPORTANT OR YOU WILL BRICK YOUR ROUTER 5. Upload the new tplink.bin to /tmp. Find a way to do it. I used a webserver and used wget to download the file into the /tmp folder. You can try using SSH since you're still on DD-WRT, but do not ask me how. Use Google for that. 6. In terminal, telnet 192.168.1.1 7. cd to /tmp 8. Run "mtd -r write tplink.bin linux" without the quotes. This process can take about 2 minutes, but may take up to 5. You'll see the command flashing between "e" and "w" As long as you see this, you're in good standing. 9. Your router will reboot when finished and you'll be at stock firmware. I would recommend doing a factory reset to be safe Smile
I followed these exact steps on my own Archer C7 V2 and all worked with success.