@Sandori You can widen of the spectrum... from 20 to 160 MHZ. Have you tested with those options? So here's the bug a boo... The advertised speeds are negotiated air time speeds and or in a perfect...

@IQBALGANIIN 500 meters? with 1 AP, not going to happen. You will need multiple APs to splash 500 meters.

@Amds You can't use the internal DNS server on for the WAN Port DNS. You enter the Local DNS Server on the VLAN DNS section.

@haswalt Change your WAN dns to google and or cloudfare. See if that helps? Confirming the ISP is solid?

@TimothyLambert Also considering going to Settings>Transmission>NAT>ALG. Disable all the ALG's and retest.

@TimothyLambert The best way to look at it is... Click on the client list and click on the 3 dots on the right. Check customized columns, check signal, wifi connection, rx, and tx. This will show you...