My ViaVersion 3.1.0 and ViaRewind 1.5.1 are on my BungeeCord (running SSBungeeCord).

My 1.7.10 user can join the lobby just fine, but as soon as he joins another server, he crashes.
Spigots between servers haven't changed. There's a tiny error in the lobby console at the bottom:

[00:37:39 INFO]: UUID of player Foulest is da47dff3-0525-4f5d-9ab5-77b7d1701dc1
[00:37:39 INFO]: Foulest[/99.145.233.13:34434] logged in with entity id 60 at ([world]1.5, 64.0, 0.5)
[00:37:45 INFO]: [CommandNPC] Sent 'Foulest' to server 'Practice'!
[00:37:45 INFO]: Foulest lost connection: Disconnected
[00:37:46 INFO]: UUID of player Foulest is da47dff3-0525-4f5d-9ab5-77b7d1701dc1
[00:37:47 INFO]: Foulest[/99.145.233.13:34486] logged in with entity id 61 at ([world]1.5, 64.0, 0.5)
[00:37:47 INFO]: Foulest lost connection: Internal Exception: java.io.IOException: Error while write(...): Broken pipe

Here's the BungeeCord log:

.... [00:37:39 INFO]: [Foulest|/99.145.233.13:59402] <-> ServerConnector [Lobby] has connected
.... [00:37:45 INFO]: [Foulest|/99.145.233.13:59402] <-> ServerConnector [Practice] has connected
.... [00:37:45 INFO]: [/99.145.233.13:59402|Foulest] <-> DownstreamBridge <-> [Lobby] has disconnected
.... [00:37:46 INFO]: [/99.145.233.13:59402|Foulest] -> UpstreamBridge has disconnected
.... [00:37:46 INFO]: [/99.145.233.13:59402|Foulest] <-> DownstreamBridge <-> [Practice] has disconnected
.... [00:37:46 INFO]: [Foulest|/99.145.233.13:59402] <-> ServerConnector [Lobby] has connected
.... [00:37:47 WARN]: No client connected for pending server!
.... [00:37:47 INFO]: [Foulest|/99.145.233.13:59402] <-> ServerConnector [Lobby] has disconnected

Here's the Practice server log:

[00:37:45 INFO]: Foulest[/99.145.233.13:38490] logged in with entity id 0 at ([world]0.5, 64.0, 0.5)
[00:37:46 INFO]: Foulest lost connection: Disconnected

Issue seems to possibly be with another plugin, TAB.
Crash report: https://pastebin.com/raw/ThDcvVvY

Client is using Lunar Client.

Here is the crash report when the client is on Minecraft 1.7.10: https://pastebin.com/raw/vZ2Yu4fz

Very different. I guess Lunar Client obfuscates everything.
TAB plugin is on the latest version released today, 2.8.4.