I've got a couple of ideas I've written out for you below:
If you've got a spare Windows machine or even a computer/laptop that you use running Windows – make a Windows share and host it for the network from that PC at an address such as:
\computername\sharedfoldername – then install SAMBA on your CentOS machine and use the command:
smbclient -L WINDOWS_COMPUTER_NAME_OR_IP_ADDRESS
as ROOT in CentOS terminal.
Make sure you have the IPv4 address or network name of that Windows machine to replace
WINDOWS_COMPUTER_NAME_OR_IP_ADDRESS with in that command. Then you could mount to a folder in CentOS or just access as a network drive.
To access as a network drive, open your file explorer on CentOS (mine is Caja) and find the location:
But replace the IP/computer name again and the windows share name. It will ask you for credentials.
You can sign in anonymously, but if you have protected folders, use the credentials from the windows machine.
(In case you don't know – to make a Windows share for the network, create a folder on a local drive on the hosting Windows machine, right click on it and find the share option, choose who you want to access (if you choose a specific user from the hosting windows machine, that is the credentials that you'll need to use for the connection from CentOS) and press share, it will give you a location path (/computername/sharedfolder/) on the network. You can access this from ANY Windows PC or CentOS machine on the network.
Locate your router and plug a hard drive/USB drive into a USB socket in the back of it. Use a Windows machine to access the drive on the network, then no machine is needed to host this and it's free. - You can access this by opening File Explorer on Windows and entering the path:
The * represents your router's IP address which is the same one as the one you will use to configure it online and will show somewhere on the back of it. Once accessed by a computer on your network, you can then see all drives plugged in – you can even MAP A NETWORK DRIVE to your WINDOWS PC by right clicking and choosing map. Then this works as a sort of shared network drive accessible by all those on the network (unless you specify which users can access) and connects automatically on Windows. Unfortunately, I don't yet know how to access this network drive from the router on CentOS or Android... – but there's some YouTube videos or online tutorials that explain how to do it but none have worked for me. I prefer option 1 because I know how to access from CentOS and it comes in handy because I have an old Windows laptop in the cupboard on sleep mode always but hosting these files. You can make as many shares as you want with it so I find it quite handy.
About Android – not sure, you may be able to find something to connect it to (possibly SAMBA) on the play store...?
Security concerns with SAMBA – I haven't noticed any and I've been using the above for a while.