You can find the setting in "Privacy & Security > Local Network" as shown here:
We've also had instances, where toggling the setting to "off" also helped resolve the issue.
PLEASE NOTE: We also strongly suggest that you update any Firewall or VPN software that you may have installed. We have also had some customers who suffered networking issues after upgrading to Sequoia that persisted until they updated their Firewall/VPN software.
Last but not least, according to the following article, "both Wireguard and Mullvad VPNs would fail to connect properly when I had a private MAC address enabled":
https://arstechnica.com/gadgets/2024/09/macos-15-sequoia-the-ars-technica-review/
The following two articles may be of use as well:
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We will continue to amend this article over time as we gain more insight.