I think this is instance communication

code/modules/client/client_procs.dm

@@ -326,12 +326,16 @@
 	if(length(related_accounts_cid))
 		log_admin("[key_name(src)] Alts by CID: [jointext(related_accounts_cid, " ")]")
 
+	// This sleeps so it has to go here. Dont fucking move it.
+	SSinstancing.update_playercache(ckey)
+
 	// This has to go here to avoid issues
 	// If you sleep past this point, you will get SSinput errors as well as goonchat errors
 	// DO NOT STUFF RANDOM SQL QUERIES BELOW THIS POINT WITHOUT USING `INVOKE_ASYNC()` OR SIMILAR
 	// YOU WILL BREAK STUFF. SERIOUSLY. -aa07
 	GLOB.clients += src
 
+
 	spawn() // Goonchat does some non-instant checks in start()
 		chatOutput.start()
 
@@ -434,6 +438,7 @@
 		GLOB.admins -= src
 	GLOB.directory -= ckey
 	GLOB.clients -= src
+	SSinstancing.update_playercache() // Clear us out
 	QDEL_NULL(chatOutput)
 	if(movingmob)
 		movingmob.client_mobs_in_contents -= mob