NYM-1502: Fix a crash when network reconnected on Windows. (#5508)

When the connection is re-established the callback thread was not running in a `tokio`-managed thread which caused a panic.

Author: trojanfoe

nym-vpn-core/CHANGELOG.md

@@ -22,7 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - [Android] Diagnostic doesn't panic because of uninitialized context (https://github.com/nymtech/nym-vpn-client/pull/5415)
-
+- [Windows] Fix a crash when the network reconnected (https://github.com/nymtech/nym-vpn-client/pull/5508)
 
 ## [1.30] - 2026-05-29
 

nym-vpn-core/crates/nym-offline-monitor/src/windows.rs

@@ -53,6 +53,7 @@ impl BroadcastListener {
             },
             notify_tx,
             pending_online_cancel: None,
+            rt_handle: tokio::runtime::Handle::current(),
         }));
 
         let state = system_state.clone();
@@ -183,8 +184,12 @@ enum StateChange {
 struct SystemState {
     connectivity: ConnectivityInner,
     notify_tx: watch::Sender<Connectivity>,
+
     /// Cancels a pending "Connected" notification during the stabilisation delay.
     pending_online_cancel: Option<CancellationToken>,
+
+    /// Tokio runtime handle to run callbacks in
+    rt_handle: tokio::runtime::Handle,
 }
 
 impl SystemState {
@@ -222,7 +227,7 @@ impl SystemState {
                 self.pending_online_cancel = Some(cancel.clone());
                 let notify_tx = self.notify_tx.clone();
                 let online_connectivity = self.connectivity.into_connectivity();
-                tokio::spawn(async move {
+                self.rt_handle.spawn(async move {
                     tokio::select! {
                         _ = tokio::time::sleep(ONLINE_STABILIZATION_DELAY) => {
                             tracing::info!("Connectivity changed: Connected");