When you get errors of missing icons like shown below, then it's the Admins job to fix his server.
Code:
<09:54:50> The icon for the server was not found.
<09:54:51> Transfer "icon_1061964305" reports: (file transfer connection timeout)
<09:54:51> The icon for server group "Bg (12)" was not found.
<09:54:51> The icon for channel "T-T Jr" (8) was not found."
Icons are missing on server side and not client side in that case.
Or file transfer is broken on server side.
See thread https://forum.teamspeak.com/threads/65614