Private Fritzbox 4040 and LTE Cube cloud storage?

I'm rather inexperienced in networking, so I ask you for help.

I have a T-Mobile HomeNet Box (Huawei E5170). Inside is a SIM card from Bob. (Austrian mobile operator, part of A1 Telekom)

A Fritzbox 4040 is connected to this HomeNetBox.

A hard drive should be connected to the Fritzbox (e.g. Via USB)

The aim is to access my data on the hard drive while out and about (e.g. Hotel WLAN). Can you tell me how I can do that? So something like a private cloud.

Do not use the FritzBox for this. Let the router be the router.

I would set up a small local server with a hard drive (even a RaspberryPi would do it, but I recommend x64 architecture. Son used ThinClient e.g.)

Since you will probably not be able to get port releases via your mobile phone, you must use a tunnel server.

Either yourself on a rented VPS (recommended) or e.g. ZeroTIER (You always need the program. Otherwise you won't get in)

And then you can e.g. Install NextCloud on the local server and thus offer the data

Sounds a bit complicated to me, do you have specific links to the devices and software I need?

I'm afraid you will need help with that.

You need some kind of system. I have e.g. Bought 2 old thin clients for around 20-30 euro each and pimped them up a bit.

the VPN. You have to see how you want it to be. I recommend renting a VPS for this. You can then host even more

Of course you can, but you only have ftp access or only NAS function from the fritzbox. But be careful: don't expect high performance and transfer rates. The fritzbox can do all that, but quite slowly because the cpu is quite overloaded is.

I recommend you: raspberry pi 4b with 4 or more GB, plus a 32GB microSD and a good USB-C 3A 5V power supply - you already have a server.

the software: raspbian lite (without graphical desktop) you install pivpn and NextCloud on it.

The problem where I see: Port sharing via LTE router and provider? Do you mean you get a port free (for VPN)? Before that, you have to be smart about it.

Thank you, that helps me a lot.

I then connect the hard drives to the Raspberry Pi via USB 3.0?

Concerning. Port release, where or how can I find out? At the internet provider or does it depend on the modem?

Would it help if I buy an LTE surf stick and connect it to the Fritzbox via USB?

If the Fritzbox supports USB-LTE function, yes it would work. Not all Fritzboxes support this.

Yes, you can then connect the hard drives via USB 3.0 (Raspi 4 has 2x 3.0).

Yes you have to read the description from the stick, if this supports port sharing, then ask the provider whether port sharing is possible.

Incidentally, you can also operate the stick directly on the Raspi, without any router in between.

Thanks for the really good help. My Fritzbox should support a USB LTE stick.

I'm going to make smart with regard to STICK and Internet providers