The captive portal page takes a long time to load for some clients and does not come up at all for others.
This may be caused by TCP timestamps being applied on the server side when clients are behind a NAT device.
To resolve this issue:
In Amigopod: go to Administrator->System Control->System Config
The copy/paste the lines below into the kernel options section right above
the line that reads: "# Controls IP packet forwarding"
# Disable TCP Timestamps to resolve slow captive portal page loads
net.ipv4.tcp_timestamps = 0
Then restart the Amigopod appliance.