Portenta H7 inconsistent connecting to WiFi (Access Point VLAN, WPA2)

Official Hardware Portenta Family Portenta H7
1

Hi everyone,

I’m struggling with unreliable WiFi connections on my Portenta H7 when connecting to an access point with VLANs.

Symptoms:

  • ScanNetworksAdvanced lists all networks correctly, including the VLAN SSID.
  • When I run WiFiWebClient, it almost never connects.
  • First connection attempt: takes ~1 minute, then returns 4 (no connection).
  • Following attempts: fail faster (~5 seconds).
  • When it does connect, the link is stable (I can run Modbus and a test web server reliably).

Setup:

  • Access point with VLAN, using WPA2 encryption.
  • Firewall in between, currently configured to accept all traffic (to allow Modbus now, and later a web interface).
  • Other devices (laptops, phones, ESP32) connect to the same SSID without issue.
  • Verified VLAN + DHCP settings, tried testing close to the AP.

Notes:

  • The firewall doesn’t seem to be blocking anything — once connected, traffic flows fine.
  • Connection issues have existed since the start of the project.

Questions:

  1. Is there a known problem with the Portenta H7 and VLAN-tagged SSIDs on WPA2?
  2. Any debugging tips to better understand why the first association fails so often?

Thanks in advance for any advice — I’d love to hear if anyone else has run into this.

Here's a minimal sketch which makes problems appear as described:

#include <WiFi.h>

char ssid[] = "MySSID";
char pass[] = "MyPassword";

void setup() 
{
  Serial.begin(9600);
  while (!Serial); 

  WiFi.disconnect();  
  delay(2000);

  int maxTries = 5;
  int attempt = 0;
  
  Serial.println("Trying to connect...");
    
  while (WiFi.status() != WL_CONNECTED && attempt < maxTries) 
  {
    Serial.println(WiFi.begin(ssid, pass));
    attempt++;
  }

  if (WiFi.status() == WL_CONNECTED) 
  {
    Serial.println("Connected!");
    Serial.print("IP-Addr: ");
    Serial.println(WiFi.localIP());

  } 
  else Serial.println("\nWifi Connection Failed!");
}

void loop()
{
}
2

Hi, when it does connect, what value to you get for WiFi.RSSI();

1 Like
3

I recently installed an extra access point nearby. I got around -40dBm while scanning for it and thought I can rule out this issue. Because of your answer, I checked my VLAN settings and noticed that I have to enable the port of my switch. Now it works just fine!!
Thanks a lot!

1 Like