RAX40 WIFI can't connect internet

Hi Support,

I am experiencing a situtation with "connected but no internet" with my RAX40 router since last Saturday (9 May 2020). It works perfectly so far since i bought it last September.

Let me illustrate the network structure below,

ISP modem -- XiaoMi Router (connected ISP modem with LAN) -- RAX40 (connected XiaoMi router with LAN).

Both XiaoMi router and RAX40 share WiFi with 2.4G and 5G

Currently, any network from XiaoMi router can connect to internet. However, RAX40 indicates that it is linked to internet (with green LED) but when i connected to RAX40's WIFI, no internet is accessed. I tried to use my laptop to connect RAX40's WIFI, WIN10 shows the error "The DNS server isn't responding".

I tried to bypass XiaoMi router and link RAX40 with my ISP modem. Turn off both, restart ISP modem 10 mins later, and then restart RAX40 another 10 mins later. Not work.

I also follow RAX40's manual to execute ipconfig/release, ipconfig/renew. Not work.

I tried to remote access RAX40 by my mobile's app (my mobile is not connected to RAX40's WIFI), it works. I run the speed test in the app and it works perfectly. (~95mb up or dl)

I wonder what's wrong with RAX40's WIFI. App proves that RAX40 is connected with internet but it's WIFI said no.

P.S. Fireware is v1.0.3.64_1.0.1

Please assist. Thanks.

Regards,

Wilson