new router, enabled remoted management, default port 8888 and all devices were selected.

disabled header check

getting 403 when attempting to access via the public ip including the port number

getting 403 when using the tplinkdns.com

times out when omitted the port (i.e. port 80) both IP and tplinkdns.com

but it does work when I set the remote HTTP port to 80 both via the public IP number and tplinkdns.com

i.e. it seems that remote management only work when the router remote managemet is set to port 80