diff --git a/src/services/wifi_service.cpp b/src/services/wifi_service.cpp
index 25b76a8..5c14496 100644
--- a/src/services/wifi_service.cpp
+++ b/src/services/wifi_service.cpp
@@ -87,7 +87,10 @@ void WifiService::applyServers(Why why) {
             touched = true;
         }
     }
-    if (!esp_sntp_enabled()) {
+    // Our own flag, not esp_sntp_enabled(): starting is only queued for the network task, and a
+    // second call that looked before it ran would start SNTP twice, which ESP-IDF asserts on.
+    if (!sntpStarted_) {
+        sntpStarted_ = true;
         esp_sntp_setoperatingmode(ESP_SNTP_OPMODE_POLL);
         esp_sntp_init();
     } else if (touched || changed) {
@@ -249,7 +252,10 @@ void WifiService::tick(uint32_t nowMs) {
 
     apply(controller_.update(nowMs, settings_.getBool(Setting::WifiEnabled) && !paused_));
 
-    if (controller_.state() == State::Connected && nowMs - serversCheckedMs_ >= kServersEveryMs) applyServers(Why::Check);
+    // Signed: serversCheckedMs_ can be newer than this pass's nowMs (set from millis() just above),
+    // and the unsigned difference then ran the check again at once, at every join.
+    if (controller_.state() == State::Connected && static_cast<int32_t>(nowMs - serversCheckedMs_) >= static_cast<int32_t>(kServersEveryMs))
+        applyServers(Why::Check);
 
     if (ntpWaiting_ && sntp_get_sync_status() == SNTP_SYNC_STATUS_COMPLETED) {
         ntpWaiting_ = false;
diff --git a/src/services/wifi_service.h b/src/services/wifi_service.h
index 5d77a84..c39864e 100644
--- a/src/services/wifi_service.h
+++ b/src/services/wifi_service.h
@@ -86,6 +86,7 @@ class WifiService : public Service {
     std::vector<ScanEntry> listScan_;
     uint32_t listScanSeq_ = 0;
     bool ntpWaiting_ = false;
+    bool sntpStarted_ = false;
     bool radioInitialised_ = false;
     bool paused_ = false;          // Debug Builds: off for a moment, whatever the setting says
     bool fixed_ = false;           // the network in use has a Fixed address