Firewall config

I'm having a bit of a problem with a firewall configuration. I'm using GUFW.

When I launch firefox and it goes to my home page (DuckDuckGo), the browser makes several connections. For example, the output of "ss -prtu":

tcp    ESTAB      0      0        10.8.8.22:32774   ec2-176-34-131-233.eu-west-1.compute.amazonaws.com:https  users:(("firefox",pid=6371,fd=146))

tcp   ESTAB      0       0        10.8.8.22:52114   ec2-54-229-110-205.eu-west-1.compute.amazonaws.com:https  users:(("firefox",pid=6371,fd=98))

As an experiment, I want to block both incoming and outgoing connections in the range 10.8.0.0/16. I added rules to GUFW and the logs reflect this:

[12/27/2017 03:37:33 AM] Editing rule (Adding): myrule | /usr/sbin/ufw deny out from any to 10.8.0.0/16 > Rule added

[12/27/2017 03:37:06 AM] Editing rule (Adding): myrule | /usr/sbin/ufw deny in from 10.8.0.0/16 to any > Rule added

I exited Firefox, then restarted firefox and it went to it's home page as normal. In a terminal, I typed ss -prtu and my firewall commands apparently failed because this comes up:

tcp   ESTAB      0      0                                   10.8.8.22:39908                ec2-176-34-135-167.eu-west-1.compute.amazonaws.com:https                 users:(("firefox",pid=9687,fd=101))

tcp   ESTAB      0      0                                   10.8.8.22:42292                a88-221-134-48.deploy.akamaitechnologies.com:http                  users:(("firefox",pid=9687,fd=6))

tcp   ESTAB      0      0                                   10.8.8.22:46624                ec2-52-72-108-51.compute-1.amazonaws.com:https                 users:(("firefox",pid=9687,fd=94))

tcp   ESTAB      0      0                                   10.8.8.22:46626                ec2-52-72-108-51.compute-1.amazonaws.com:https                 users:(("firefox",pid=9687,fd=95))

Any idea what I'm doing wrong?

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