Zerotierone: Bug / Feature: MTU should default to 1280 or 1390

[unquietwiki]

• https://blog.cloudflare.com/increasing-ipv6-mtu/
• https://cloud.google.com/vpn/docs/concepts/mtu-considerations
• https://docs.microsoft.com/en-us/azure/virtual-network/virtual-network-tcpip-performance-tuning

With the default MTU of 2800 on ZeroTier interfaces; as of mid-2019, cloud-providers still have issues properly handling VPN tunnels, as well as fully supporting IPv6 traffic. Google appears to suggest using 1390 (70 less than their 1460 limit on instances); Azure and Cloudflare both use/recommend 1400. Using 1280 doesn't seem to be required in these environments at least; it might be necessary for other environments.

Alternatively, maybe there's some kind of lookup table/intelligence, that could be deployed to help users avoid connectivity issues?

[adamierymenko]

This is fixed in dev which is shipping shortly. The UDP MTU default is now 1432 and works fine on all these AFIAK.

[unquietwiki]

Thanks @adamierymenko for addressing this!

[alatteri]

This is fixed in dev which is shipping shortly. The UDP MTU default is now 1432 and works fine on all these AFIAK.

@adamierymenko
As of 1.4.6 new networks are still defaulting to MTU 2800. Is 1432 default still in yet to be rolled in?