How random is random? (Beryl MT3000 & Hotsplots)

Routers
1

Hi everyone,

I use my Beryl (MT3000) every morning on the bus to work. The bus operator uses Hotsplots, which offers 100MB/24h per device.

I set the Beryl to "Randomize MAC address at reboot". However, in 90% of cases, I still get these error messages from the captive portal:

  • "You are already connected at another location"

  • "You have already used 100MB of your 100MB"

My Workaround: Instead of letting the Beryl randomize at reboot, I manually type a new MAC address into the MAC Clone field. As soon as I do this manually, it works without a problem and I get a fresh 100MB session.

My Question: If the "Randomize at reboot" feature actually creates a new MAC, why does the portal still recognize me? Does the Beryl perhaps reuse certain MAC prefixes (OUI) that are already flagged, or is the randomization not as "random" as it should be?

Has anyone else experienced this with public WiFi portals?

Thanks
Marcus

2

Did you check the mac addresses that its generating? If so do you see them being different every time?

Are you deleting the wifi profile and then reconnecting to the wireless network or just turning on the device and letting it auto connect from the day before?

What firmware are you running on the router in question?

3

Sounds like @buntspext is reconnecting to a saved profile? If so that would explain the behaviour as the docs state the random MAC is saved into the connection profile for the SSID not randomised on each connection.

MAC Mode

You can choose which MAC the router uses to connect to the public hotspot.

  • Factory: Uses the device's original factory-assigned MAC address.

  • Clone: Clones a client device’s MAC address for connection. If the desired MAC isn’t listed, manually enter the address you want to clone.

    Note: Many modern devices use randomized MAC addresses (often called Private Wi-Fi Address or random hardware address) when connecting to Wi-Fi networks. Because of this, the MAC address displayed here may not match the device’s actual physical MAC.

  • Random: Automatically generates a random MAC address for connection.

When saving the network configuration, the MAC Mode (including any cloned/randomized MAC address) is tied to the specific SSID you save. You can manually change these settings for each SSID at any time.