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fabianishere / udm-iptv

Helper tool for configuring routed IPTV on the UniFi Dream Machine (Pro)
GNU General Public License v2.0
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UDM WAN pppo MTU and udm-iptv #68

Closed StreborStrebor closed 2 years ago

StreborStrebor commented 2 years ago

The UDM by default sets ppp0 with MTU 1492, eth4 with MTU 1500 and eth4.6 MTU 1500

To avoid broken VPN tunnels and other issues, it's desired to set: eth4 mtu 1512 eth4.6 mtu 1508 ppp0 mtu 1500

This (onboot) script does that:

sed -i 's/ 1492/ 1500/g' /etc/ppp/peers/ppp0
ip link set dev eth4 mtu 1512
ip link set dev eth4.6 mtu 1508
ifconfig eth4 down
ifconfig eth4 up
killall pppd

After running this script (manually or with onboot) checking the MTU with this page ( http://www.letmecheck.it/mtu-test.php ) shows the ppp0 MTU is increased to 1500. VPN tunnels and heavy traffic really like this.

However, the udm-iptv (v 2.04) script does not. It breaks KPN TV.

Any chance you could take a look at what is breaking? Any way to get these two to work in harmony?

Some good background info on the unifi community forum can be found here: https://community.ui.com/questions/Feature-Request-UDM-Pro-PPPoE-RFC4638-1500-MTU-MRU-for-PPP/b5c1fcf6-bee5-4fc7-ae00-c8ce2bf2e724

fabianishere commented 2 years ago

Is the script giving you any errors? Could you post the output of udm-iptv-diag?

I suspect you need to adjust the MTU of the iptv VLAN interface as well.