diff --git a/src/main/java/net/frozenorb/apiv3/model/User.java b/src/main/java/net/frozenorb/apiv3/model/User.java
index d33ba72..1845490 100644
--- a/src/main/java/net/frozenorb/apiv3/model/User.java
+++ b/src/main/java/net/frozenorb/apiv3/model/User.java
@@ -313,9 +313,13 @@ public final class User {
         return true;
     }
 
-    public void leftServer() {
-        this.lastSeenAt = Instant.now();
-        this.online = false;
+    public void leftServer(Server server) {
+        // We have this check to prevent issues where one server's
+        // leave is processed after another server's login.
+        if (server.getId().equals(lastSeenOn)) {
+            this.lastSeenAt = Instant.now();
+            this.online = false;
+        }
     }
 
     public void startPasswordReset() {
diff --git a/src/main/java/net/frozenorb/apiv3/route/servers/POSTServersHeartbeat.java b/src/main/java/net/frozenorb/apiv3/route/servers/POSTServersHeartbeat.java
index aac63fd..87690c4 100644
--- a/src/main/java/net/frozenorb/apiv3/route/servers/POSTServersHeartbeat.java
+++ b/src/main/java/net/frozenorb/apiv3/route/servers/POSTServersHeartbeat.java
@@ -13,6 +13,7 @@ import lombok.extern.slf4j.Slf4j;
 import net.frozenorb.apiv3.APIv3;
 import net.frozenorb.apiv3.actor.Actor;
 import net.frozenorb.apiv3.actor.ActorType;
+import net.frozenorb.apiv3.actor.actors.ServerActor;
 import net.frozenorb.apiv3.model.*;
 import net.frozenorb.apiv3.unsorted.BlockingCallback;
 import net.frozenorb.apiv3.unsorted.FutureCompatibilityCallback;
@@ -33,7 +34,7 @@ public final class POSTServersHeartbeat implements Handler<RoutingContext> {
             return;
         }
 
-        Server actorServer = Server.findById(actor.getName());
+        Server actorServer = ((ServerActor) actor).getServer();
         ServerGroup actorServerGroup = ServerGroup.findById(actorServer.getServerGroup());
         JsonObject requestBody = ctx.getBodyAsJson();
         Map<UUID, String> playerNames = extractPlayerNames(requestBody.getJsonArray("players"));
diff --git a/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLeave.java b/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLeave.java
index 0127bba..8534205 100644
--- a/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLeave.java
+++ b/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLeave.java
@@ -3,6 +3,10 @@ package net.frozenorb.apiv3.route.users;
 import io.vertx.core.Handler;
 import io.vertx.ext.web.RoutingContext;
 import net.frozenorb.apiv3.APIv3;
+import net.frozenorb.apiv3.actor.Actor;
+import net.frozenorb.apiv3.actor.ActorType;
+import net.frozenorb.apiv3.actor.actors.ServerActor;
+import net.frozenorb.apiv3.model.Server;
 import net.frozenorb.apiv3.model.User;
 import net.frozenorb.apiv3.util.ErrorUtils;
 
@@ -10,13 +14,22 @@ public class POSTUsersIdLeave implements Handler<RoutingContext> {
 
     @Override
     public void handle(RoutingContext ctx) {
+        Actor actor = ctx.get("actor");
+
+        if (actor.getType() != ActorType.SERVER) {
+            ErrorUtils.respondGeneric(ctx, 400, "This action can only be performed when requested by a server.");
+            return;
+        }
+
+        Server actorServer = ((ServerActor) actor).getServer();
+
         User.findById(ctx.request().getParam("id"), ((user, error) -> {
             if (error != null) {
                 ErrorUtils.respondInternalError(ctx, error);
             } else if (user == null) {
                 ErrorUtils.respondNotFound(ctx, "User", ctx.request().getParam("id"));
             } else {
-                user.leftServer();
+                user.leftServer(actorServer);
                 user.save((ignored, error2) -> {
                     if (error2 != null) {
                         ErrorUtils.respondInternalError(ctx, error2);
diff --git a/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLogin.java b/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLogin.java
index 09ca685..b59fe64 100644
--- a/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLogin.java
+++ b/src/main/java/net/frozenorb/apiv3/route/users/POSTUsersIdLogin.java
@@ -7,6 +7,7 @@ import io.vertx.ext.web.RoutingContext;
 import net.frozenorb.apiv3.APIv3;
 import net.frozenorb.apiv3.actor.Actor;
 import net.frozenorb.apiv3.actor.ActorType;
+import net.frozenorb.apiv3.actor.actors.ServerActor;
 import net.frozenorb.apiv3.model.IpLogEntry;
 import net.frozenorb.apiv3.model.Server;
 import net.frozenorb.apiv3.model.User;
@@ -40,7 +41,7 @@ public final class POSTUsersIdLogin implements Handler<RoutingContext> {
             return;
         }
 
-        Server server = Server.findById(actor.getName());
+        Server actorServer = ((ServerActor) actor).getServer();
 
         if (!IpUtils.isValidIp(userIp)) {
             ErrorUtils.respondInvalidInput(ctx, "IP address \"" + userIp + "\" is not valid.");
@@ -84,7 +85,7 @@ public final class POSTUsersIdLogin implements Handler<RoutingContext> {
 
         user.updateUsername(username);
 
-        user.getLoginInfo(server, userIp, (loginInfo, error) -> {
+        user.getLoginInfo(actorServer, userIp, (loginInfo, error) -> {
             if (error != null) {
                 ErrorUtils.respondInternalError(ctx, error);
             } else {