@AbdulAdil Is there any thing can be found on the controller log? Only the WAN down? For PPPoE connection you can try to use a smaller MTU, like 1480 or 1460. Are you able to ping a public DNS when...

@dcs730 Try 8.8.8.8 as the primary DNS; Check the WAN IP of your ER6120, if it is a private IP, try to modify your modem as pure modem. Double NAT may cause DNS lookup issue. I can't really explain...

@kumarullal What is the firmware of your router? The newest firmware of ER7206 and ER605 V2 has "stateful ACL" ER605 v2.1.0 Beta Firmware Release

@Nottysfriend Make sure all these EAPs are managed by your controller. Their status on the controller should be Connected. Then try to create a 5Ghz only SSID, and test if it will happen again on...

@AdminSBO I'm not using 4G modem so I did not notice this issue before. I think you should send this topic to "Request&Suggestion" block so we can vote for you

@ElvisV If you want to change the Mac address list, note you need to remove this list from the MAC filtering/Access Control that used this list before.