diff --git a/src/pages/config.tsx b/src/pages/config.tsx
index 72378b0f..1511e893 100644
--- a/src/pages/config.tsx
+++ b/src/pages/config.tsx
@@ -41,6 +41,33 @@ const urlValidationFn = (value: string): Error | null => {
   }
 }
 
+/**
+ * Converts newline delimited URLs to an array of URLs, and validates each URL.
+ */
+const singleUrlValidationFn = (value: string): Error | null => {
+  try {
+    const urls: string[] = convertUrlInputToArray(value)
+    let i = 0
+    if (urls.length === 0) {
+      throw new Error('At least one URL is required. Reset the config to use defaults.')
+    }
+    if (urls.length > 1) {
+      throw new Error('Only one URL is allowed. Reset the config to use defaults.')
+    }
+    try {
+      urls.map((url, index) => {
+        i = index
+        return new URL(url)
+      })
+    } catch (e) {
+      throw new Error(`URL "${urls[i]}" on line ${i} is not valid`)
+    }
+    return null
+  } catch (err) {
+    return err as Error
+  }
+}
+
 /**
  * Converts newline delimited patterns of space delimited key+value pairs to a JSON object, and validates each URL.
  *
@@ -188,13 +215,13 @@ function ConfigPage (): React.JSX.Element | null {
           localStorageKey={LOCAL_STORAGE_KEYS.config.enableWebTransport}
           resetKey={resetKey}
         />
-        {/* TODO: we should only accept a single router URL */}
+        {/* For now we only accept a single router URL */}
         <LocalStorageInput
           className="e2e-config-page-input e2e-config-page-input-routers"
           description="A newline delimited list of delegated IPFS router URLs."
           localStorageKey={LOCAL_STORAGE_KEYS.config.routers}
           label='Routers'
-          validationFn={urlValidationFn}
+          validationFn={singleUrlValidationFn}
           defaultValue={convertUrlArrayToInput(defaultRouters)}
           preSaveFormat={newlineToJsonArray}
           postLoadFormat={jsonToNewlineString}