@suppenkasper0815 IPv6 problem is due to bugs in OpenWrt itself, for now I don't know how to solve it.
New versions of images based on OpenWrt 21.02.7 with kernel 5.4.238
Full sources with feeds: https://github.com/zuzia-dev/Easybox-904xDSL-repo-source/blob/main/Source/Easybox-904xDSL-full-source-openwrt-21.02-v2.zip
GH: https://github.com/OpenWrt-Repository/openwrt
The package repository is available online via Github. Good news - 2.4 GHz Wi-Fi is working again (default password: WiFipassword). Change password only via vi or mcedit (Luci is still incompatible with Wi-Fi). Bad news - MAC addresses for LAN and WAN are just an example, but everything works. Note to purists. I know this is a dirty workaround, but without DSA support, further development is not possible. Unfortunately I don't know how to add DSA support, help is needed.