Sorry; link to topic in dutch.

Zyxel VMG8825-T50 USB functie | T-Mobile Community (t-mobile.nl)

Format disc in (ex)FAT32

Connect disc to the Blue USB (3.0) connector.
Has the seagate drive his own power supply? The blue USB port may not have enough juice to power a harddrive.
I have an old 2.5 inch laptop drive who only powers up on the blue port.

As your Seagate is not showing up try changing USB cable.

Are the 2 partitions needed? Maybe de Zyxel can't handle that

Hi! That’s the model I use: https://www.bol.com/nl/p/seagate-expansion-portable-1tb-externe-harde-schijf-zwart/9200000042865291/

It doesn’t have a separate power supply. Do you maybe know if it still should work? 

I already tried repartitioning, unfortunately it doesn’t work. The (now) one partition is also in exFat. 

The USB cable works fine with my Mac. I’m running out of ideas -.-

Start with test to see if the USB port is working.

Connect a usb pendrive/usb-stick to see if the port is working.

If low power is the problem you could try to connect via a powered usb hub

Like this one

If the pendrive/usb-stick does not connect either, the modem could be faulty. In that case start with a factory reset on the modem to make sure all the bits are setup properly.

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Factory reset Zyxel

1. Use a toothpicker/paperclip to press Reset (behind powerknop on the backside left). Keep pressed until all lights, except power go out.

2. After 10 seconds release reset button. All settings should be restored to factory default.

3. Check to see if modem is in service again, (takes approx.3 minutes) Sticker at the backsite tells  default username and password to login.

Try reconnecting on the BLUE usb port.

If all of this fails, the modem USB port is faulty, Ask moderator or Helpdesk to replace.

Will try! Thanks a lot!

FYI tried out both suggestions - didn’t work.

Talked to helpdesk now and will receive a new modem. 

Thanks a lot for the help, yalerta! Will keep this thread posted

@maxtenzin 

Thanks for keeping me informed

******** UPDATE got a voicemail that I’ll receive a new modem.

FYI I was just informed by the customer service that they don’t support faulty modems if the USB port is broken. That was the answer after I called about 6 times and received a switch board, which didn’t tackle the issue at all (it only has LAN ports).

This is a terrible service! 

Does anyone have any advice how to get this fixed? 

 Hi @yalerta, 

got a new modem, but also this one can’t detect my hard drive. Do you have any other ideas what could be done? 

Thanks!

Did you change the modem AND power supply?

To be honest, the power supply will be sufficient for the modem and a connected USB stick. Connecting a real harddrive will probally have the supply to its limits and it's a matter of luck if it works.

So next question, is it possible to externaly power the hard drive?

Hey! I bought the USB switch that you posted before (https://tweakers.net/pricewatch/481495/konig-4-poorts-powered-usb-30-hub.html)

That should take care of the power supply, right? 

It should.