WR21的产品支持页 https://www.digi.com/products/cellular-solutions/cellular-routers/digi-transport-wr21#productsupport
使用flashwriter升级WR21固件
使用flashwriter能清除WR21原有的一切配置，使WR21真正恢复出厂设置。要用该方法升级WR21，请从官网下载flashwriter FlashWriter ver. 1.0.503 Application
你还需要下载WR21对应的FlashWriter的固件：http://ftp1.digi.com/support/firmware/wr21-flashwriter-52156.zip