@Milesh You may send an email to support.forum@tp-link.com to ask for further suggestions and help.

@Milesh Sorry my bad. This setting would have mattered if your AP routers were set to Smart IP(DHCP) and you have made an Address Reservation on the main router for them. Sometimes to detect Internet...

@Milesh On the main router DHCP Server set Primary DNS: 8.8.8.8 , Secondary DNS: 1.1.1.1 Keep the connection: main router LAN port => AP router WAN port Test again.

@ECKS Move the ethernet cable to another LAN port of the modem or if that doesn't improve things, change the ethernet cable (use Cat 5E or Cat 6) and test again.

@Milesh This FW version (1.1.4) has been published for the US region since the beginning of November last year. I presume it's not much different than the same FW release for the EU region. Can you...

@rariyuda Yes, it is - check this FAQ and you'll understand why.