gnirehtet: Panic "Not an Ipv4 packet, version=" when using Ookla Speedtest app

When attempting to do some comparison speed tests through the Ookla Speedtest app, the relay server crashes as soon as the test is begun in the app (the apps location/server discovery seem to work fine). General web browsing, and other speed test services appear to work fine.

Attached is stack trace from RUST_BACKTRACE=full, using latest released linux64 version from Github. The error message version=x changes - I have seen it as 0, 5, and 7. 0 seems by far the most common. Not sure why the stacktrace is being so unhelpful - let me know if I need to recompile with some additional debug headers. I’m not familiar with Rust specifically but am a systems developer so any pointers to helpful flags and I should be able to recompile if needed.

Test device is a Samsung Galaxy S5, Android 6.0.1. I can test on a variety of others if useful.

thread 'main' panicked at 'Not an Ipv4 packet, version=7', src/relay/ipv4_packet_buffer.rs:40:13
stack backtrace:
   0:     0x5583b34b4c18 - <unknown>
   1:     0x5583b34b42d3 - <unknown>
   2:     0x5583b34b3dff - <unknown>
   3:     0x5583b34b3dac - <unknown>
   4:     0x5583b34a56df - <unknown>
   5:     0x5583b34a0bfa - <unknown>
   6:     0x5583b348daa9 - <unknown>
   7:     0x5583b3495f2e - <unknown>
   8:     0x5583b34d4bc3 - <unknown>
   9:     0x5583b3496d5e - <unknown>
  10:     0x7f8aa1f97b97 - __libc_start_main
  11:     0x5583b348c16a - <unknown>
  12:                0x0 - <unknown>