Captive Portal with MAC Address "Allow" causes downloads to fail

[mibsy]

I saw a mention of this for earlier releases (18.1), but none for 18.7. I set up the Captive Portal with no authentication (just the splash page with an "Accept" button). It works fairly well, but if I allow any device by MAC address then downloads over a few Megabytes fail (I've confirmed on both a Mac and Windows PC. I can assign them a static IP through DHCP, and allow the machine by IP address and that works fine.

The only thing I noticed is that both the previous poster and I have setup the "guest" network utilizing VLANs, which may be related. I have a VLAN9 that contains my guest network and assigned it as a separate interface and then run the captive portal on eth2_vlan9. I have a second VLAN for the internal wireless - vlan5. I would prefer to utilize MAC address "allows" over the IP address, but can't until the large downloads item is addressed.

Any thoughts?