ZT at same time as LAN to LAN VPN: Performance oddities

VPN
1

I’m wondering why latency (PING Time) on my ZeroTier network is reduced by disconnecting and then reconnecting the ZT client to the ZT network on my PC. Let me give some context:

I have a remote site, connected to the Internet via 4G (Draytek 2620 4G router). It has no public IP address (CGNAT).

At home, I have a Draytek 2862 router; there is a DDNS address associated with it.

Configured in the two routers is a Draytek LAN to LAN VPN which ‘dials out’ from the remote site to my home router. This all works fine, except that the equipment I run over the network (ham radio stuff) requires network connectivity for Level-2 UDP broadcast packets, which the Draytek VPN does not support.

Therefore, I have a ZT network - I run a ZT client on my PC at home and I have a ZT/LAN Bridge running on a RPi at the remote site to connect to the equipment. It all works great but I notice a strange performance issue.

The LAN to LAN VPN is ‘always on’ between the routers and the PC automatically joins the ZT network when I boot it up.

Avg. PING time immediately after boot-up between the home PC and remote site: 86mS.

If I disconnect the home PC from the ZT network, Avg. PING times between the two sites (i.e. relying only on the LAN2LAN VPN): 52mS

If I reconnect the home PC to the ZT network, Avg. PING times: 55mS

In summary, after PC boot-up the network connection is more than 50% slower before I recycle the ZT network connection. I get better network performance after I have disconnected and then reconnected to the ZT network.

If I disconnect the Draytek VPN completely and connect only on the ZT network, Avg. PING time is 95mS i.e. higher than when the LAN2LAN VPN is connected and similar to the PING time after booting up the PC.

I’ve been watching this for over a year, so I know the phenomenon is consistent. The ham radio gear works OK after the reconnect so I know it must be using the ZT network for communication of the L2 UDP packets.

So a few questions:

  1.  Any ideas why the PING is shorter after a ZT network disconnect & reconnect? (with LAN2LAN VPN connected).

  2.  Is there a way to get the quicker connection from the start?

  3.  Is there a way to get the ZT network as fast as the LAN2LAN VPN when the LAN2LAN VPN is not present? Nothing is physically changing when the LAN2LAN network is disabled.
2

Hi there! Thanks for your post.

As much as we at ZeroTier love Reddit, we can’t keep our eyes on here 24/7. We do keep a much closer eye on our community discussion board over at https://discuss.zerotier.com. We invite you to add your questions & posts over there where our team will see it much quicker!

If you’re reporting an issue with ZeroTier, our public issue tracker is over on GitHub.

Thanks,

The ZeroTier Team

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.