Slower speeds even when devices on same WiFi


I’m using ZT to share selfhosted apps with my family.

While sharing media files, I noticed that transfer speeds are slow even when devices are on the same local WiFi.

To investigate, I set up Librespeed on my laptop. Then I did speedtests via my Android phone, connecting to my laptop. Both devices are on my home WiFi router which supports ~100Mbit/s speed between devices.

  • Upon accessing the speedtest service via ZT IPv4 address (10.243.x.x), I get ~30Mbit/s. Coincidentally, this is in fact the maximum upstream speed my ISP plan allows me. Not sure if this is related.
  • Upon accessing speedtest service via local router IPv4 address (192.168.x.x), I get ~100Mbit/s, which is what I’ll expect since this is what my router supports.

I don’t know exact overhead of encryption on ZT, but getting only one-third network bandwidth seems too less.

I checked sudo zerotier-cli peers which shows me “DIRECT” connection to phone, beside its local IPv4 address as I would expect.

200 peers
<ztaddr>   <ver>  <role> <lat> <link>   <lastTX> <lastRX> <path>
62f865ae71 -      PLANET   111 DIRECT   4583     199706
778cde7190 -      PLANET   242 DIRECT   19600    199565   2605:9880:400:c3:254:f2bc:a1f7:19/9993
aaaaaaaaaa 1.12.2 LEAF     376 DIRECT   16463    16463    aaaa:aaaa:aaaa:aaaa:aaaa:aa:aaaa:aaaa/39787
cafe04eba9 -      PLANET   182 DIRECT   19600    199617
cafe9efeb9 -      PLANET   298 DIRECT   19600    199500   2605:9880:200:1200:30:571:e34:51/9993
aaaaaaaaaa 1.12.0 LEAF     204 DIRECT   4583     4369

Last one is my phone. I intentionally changed the path for the first LEAF and ztaddr for both before posting here.

My phone has MIUI 12.0.3, Android version 10. The ZT version as reported on footer of application is 1.12.0-3. I installed it via Play Store.

On my laptop, I have EndeavourOS. zerotier-one -v shows 1.14.0.

Is there any way I can go about troubleshooting this issue?


tl;dr - Even when devices are on same WiFi, I get one third the speed that my router can support, if I use ZT.