Google Classroom Video not making it through firewall

Hello,

My name is Harold. I use a dedicated PC to provide IP Forwarding, DHCPD 
and Firewall services for my home. All communications with the outside 
world go through this PC. Lets call this PC#1. PC#1 has Slackware 14.2 
x64 installed on it with all of the latest updates. I have a second PC, 
identical hardware as PC#1, that has Slackware 15.0 x64 installed on it 
again with all of the latest updates. Lets call this PC#2.

My child uses Google Classroom to participate in on-line school. With 
PC#1 connected to my network, normal two-way video and audio 
communications between the teacher and my child are possible. When I 
replace PC#1 with PC#2, the video that is generated locally does not 
make it to the teacher. The teacher sees a blank screen. My child is 
able to see video received from the teacher. Audio continues to behave 
normally, that is the teacher and my child are able to communicate 
verbally.

For PC#1 and PC#2 I am able to use identical initialization scripts, 
except for rc.inet1.conf which has updated formatting on PC#2. For the 
Firewall services, I utilize Shorewall with the same scripts for both 
PC's.

FaceTime between a couple of ipads works just fine.

I've provided shorewall dumps for both PC's. If I could get some insight 
as to how to log the interaction that is not working, I would greatly 
appreciate it.

Thank you for your time!

Harold