It is done and the self compiled OpenWRT 19 firmware works

 

    Setup a TFTP Server https://openwrt.org/docs/guide-user/troubleshooting/tftpserver
     
    You have to start the board with UART
    On start you press fast a key
        (ipq44xx) 

 

tftpboot openwrt-ipq40xx-compex_wpj419-nand-squashfs-nand-factory.ubi
nand erase.chip; nand write ${fileaddr} 0x0 ${filesize}
set fsbootargs ubi.mtd=rootfs root=/dev/ubiblock0_1 rootfstype=squashfs
saveenv
res

 

Everything is working fine

 

    Now: you have  OpenWRT with Version 19.07.4 and LINUX Kernel 5.4.77

 

    Then i updated the network file /etc/config/network with my tagged VLAN 

https://openwrt.org/docs/guide-user/network/vlan/switch_configuration

 

(Section: Creating driver-level VLANs)

 

    Then i configured my WIFI in /etc/config/wifi

 

 

Now, i have a perfect WIFI with tagged VLAN (802.1q)

 

One Problem: i can not install LuCI ☹