The correct way to go about it would be to put your BGW210 in IP Passthroug mode so only Netgate PFSense were exposed. You'll need to find MAC address of your PFSense and make appropriate changes to BGW210:
On your DNS speculations, by default modern Netgate PFSense uses Unbound and its setup as DNS Resolver mode. It can work as full resolver or forward-only (say if you insist on using 8.8.8.8 or 1.1.1.1 fully recursive-resolver for doing on the work) - but you need to check Enable Forwarding Mode under Service > DNS Resolver. These are well documented at
https://docs.netgate.com/pfsense/en/latest/services/dns/resolver.htmlBGW210 or BGW320 (taken from
https://www.att.com/support/article/u-verse-high-speed-internet/KM1322413/) can be set to DMZ mode.
From a computer connected to your Wi-Fi gateway:
Go to your gateway settings.
Select Firewall and then Advanced.
Enter your Device Access Code, if asked. You can find this on a sticker on your gateway.
Turn off everything in Firewall Advanced.
Select IP Passthrough and set the following:
Allocation Mode to Passthrough
Passthough Mode to DHCPS-fixed
Enter the MAC address of the device to be set up in the Passthrough Fixed MAC address field.
Select Save and Restart Now.
Good to know: You may have to reboot your computer and Wi-Fi gateway to force a new IP assignment.
if this doesn't work then might want to look at mapping
since it's PF based, what does /etc/pf.conf looks like on netgate PFSense?
You might want to use tcpdump on /dev/pflog0 to troubleshoot and see what exactly your rules are missing (or insight on rules that isn't working as it should).
good place to start would be
https://docs.netgate.com/pfsense/en/latest/diagnostics/packetcapture/tcpdump.htmlBut these are advanced kung-fu that I don't think average user would possess. (more likely firmware / Embedded DevOp)