I'd like to express general caution with upgrading to 21.02 on Linksys WRT-series routers; the Marvell "open-source" firmware isn't truly open source (it has proprietary binary blobs) and development seems to have halted sometime in 2020.

Many users report Wi-Fi connectivity issues[0]. When I did an upgrade, I was unable to connect my laptop and Roomba to wifi, and had to rollback to 19.07.8.

[0] https://github.com/kaloz/mwlwifi/issues