On the left side is my original network config from 17.07.7 and on the right side the new not working config (after open menu "interface" in 21.02_rc2).
I used the newest snapshot from today: openwrt-21.02-snapshot-r16130-1b27d89d40-ath79-generic-tplink_archer-c7-v2-squashfs-sysupgrade.bin
Uwe