ongoing IPv6 Facebook/Meta network troubles over PPPoE

[raceybe]

I seem to be experiencing the same issue that others see with Facebook regarding packet loss or failed connections. If I disable IPv6 my connection works great. With the tunnel, it works well in most places, but often fails with Facebook/Meta networks (including Instagram, etc.). Pages don't finish loading, multiple refreshes required, etc.

I have fibre over PPPoE and noticed the default MTU of 1480. Due to the PPPoE link, I figure it is logical to reduce the HE tunnel by 8 bytes to 1472. I have configured that, and further implemented clamping on my router at 1412 (1432 for IPv6, minus another 20 bytes).

Is there anything I'm doing wrong? The connection works well for the majority of situations. It's running on a Ubiquiti ER-X. I used the default configuration from the Tunnel Broker account, with the addition of setting the MTU to 1472.