for example, the device NETGEAR R6700 v2, when you select the version 21.02.7, it will show the message with red color
Failed to fetch https://downloads.openwrt.org/releases/21.02.7/.overview.json
but, when older version 21.02.5, it shows right page contents
anyone know why?
Well, the file referenced in the error is legitimately missing from the downloads server in the 21.02.7 directory, but it is there for 21.02.5. So the firmware selector's error is reflecting the underlying reality of the downloads server.
I cannot tell you why the file is missing, though.
But... why are you using a very old, EOL, and unsupported version? The R6700 is supported by the latest (25.12), so there really isn't a good reason to be using such old firmware.
thanks for the comments.
another strange thing is that once worked version no longer available. due to the apk introduced in 25?
the new https-dns-proxy package sometime has issue when DNSSEC is enabled and reverse DNS is broken https://github.com/aarond10/https_dns_proxy/issues/199 . the version in 21 works fine. also, the openwrt on this system is for router, WiFi is disabled so no need for new driver