In the corresponding folder you will find two files. The factory-to-ddwrt file is to flash the router from OEM to DD-WRT, which is the one we used in the first installation. The webflash file is to upgrade when already running DD-WRT and is the one we need now. In my case I downloaded:
The Linksys WRT1900ACS is a good wireless router, but one of its best features is that it is supported by different open source firmwares including dd-wrt. So, if you’re like me and want to use this router with the OpenSource router firmware to unlock all of its power instead of the limited factory firmware, read this guide to learn how to install it. It’s not a hard process but I had several issues when I installed the firmware on my router so I’ve written in this guide all the solutions I had to apply. I hope they will help you too.