diff --git a/server/src/resolvers/AccessPoint.js b/server/src/resolvers/AccessPoint.js
index 9142649..d86c617 100644
--- a/server/src/resolvers/AccessPoint.js
+++ b/server/src/resolvers/AccessPoint.js
@@ -21,7 +21,7 @@ export const AccessPoint = {
   subnetInfo: parent => getSubnetInfo(parent.ip),
 
   usage: (parent, data, context, info) =>
-    parent.usage ? parent.usage.toString() : 0,
+    parent.usage ? parent.usage?.toString() : 0,
 
   stats: async (parent, { take, dateIn, dateOut }, context, info) => {
     if (!dateOut) {
diff --git a/server/src/resolvers/AccessPointStats.js b/server/src/resolvers/AccessPointStats.js
index 8ee54a9..8f668b2 100644
--- a/server/src/resolvers/AccessPointStats.js
+++ b/server/src/resolvers/AccessPointStats.js
@@ -1,7 +1,7 @@
 const AccessPointStats = {
-  timestamp: parent => parent.timestamp.toString(),
-  avgUsage: parent => parent.avgUsage.toString(),
-  sumUsage: parent => parent.sumUsage.toString()
+  timestamp: parent => parent.timestamp?.toString(),
+  avgUsage: parent => parent.avgUsage?.toString(),
+  sumUsage: parent => parent.sumUsage?.toString()
 }
 
 export { AccessPointStats }
diff --git a/server/src/resolvers/WifiDevice.js b/server/src/resolvers/WifiDevice.js
index a162e81..bc13654 100644
--- a/server/src/resolvers/WifiDevice.js
+++ b/server/src/resolvers/WifiDevice.js
@@ -15,7 +15,7 @@ const WifiDevice = {
       })
     ).user,
 
-  usage: parent => parent.usage.toString(),
+  usage: parent => parent.usage?.toString(),
 
   accessPoint: async parent => {
     try {