time capsule/ file server

Unfortunately, Apple does not offer instructions or support for this type of connection with the Time Capsule, but some users have been able to make this work. For example, see the instructions in the link just below from expert user Tesserax:

AirPort Disk - Remote Access (4 Methods) - Apple Community

I may be able to help......IF......you are using.......

1) A simple modem......(the kind with only one Ethernet port)

2) You have a fixed Public IP address provided by your ISP......(which often requires a business account)

3) Your Time Capsule is acting as the "main" router on your network.....or....you have another Apple AirPort router acting as the "main" router on your network and the Time Capsule is set up in Bridge Mode.

Please clarify if your current setup might meet the requirements above.

Unfortunately, Apple does not offer instructions or support for this type of connection with the Time Capsule, but some users have been able to make this work.

I may be able to help......IF......you are using.......

1) A simple modem......(the kind with only one Ethernet port)

2) You have a fixed Public IP address provided by your ISP......(which often requires a business account)

3) Your Time Capsule is acting as the "main" router on your network.....or....you have another Apple AirPort router acting as the "main" router on your network and the Time Capsule is set up in Bridge Mode.

Please clarify if your current setup might meet the requirements above.

A few things to add to Bob's comments ...

This is possible, but highly not recommended due to security reasons. When accessing a file server, you will be using the SMB protocol to transfer those files. The Apple Time Capsule only supports SMB 1.0 ... which is very insecure, and only should be used on a local network.

Having a dynamic WAN-side IP address can be overcome by using a DDNS service, which will assign a "static" domain name in lieu of the dynamic address that your ISP has provided you. This typically has a cost associated with it.

To "secure" that SMB connection over the Internet, you would need to use a VPN tunnel between your remote client and your home's main router. Does that router support "client-to-server" tunnels? If it does, then it would need to be configured to allow access to clients (in this case the TC) on your local network via that tunnel.