Sysupgrade vs PPPoE: redial / hang-up problems with fast booting devices (Xiaomi AX3200 (mediatek/mt7622, 22.03), Xiaomi AX3600, Dynalink DL-WRX36 (ipq807x/generic))

I have to add that I'm using only ipv4 to prevent the ipv6 to fail and I sometimes I encounter the same problem than you, the wan interface fails and I have no connection. I power off the router for 5 mins and then I have a new ip. So ipv4 also fails after a while.