@Doublel70 

you possibly didnt include enough info in your question to entice an answer...

 

windows, Linux, or Mac ?

 

How are you trying to add more media files?

 

How did you originally add them?

 

 (filemanager/explorer, grsync, rsync, filezilla?)

 

Does your usb show up when you log into web interfce and navigate to USB?

 

Are you using it as a share, ftp local, etc?

 

Is port 21 open for ftp?

 

Is port 445 open for smb?

 

Did you check that you configured correct permissions? read and write , enable secure sharing

 

 I use Linux, and have found the most convient way is to use gvfs with file manager, very easy and straight forward to read/write/pull/push fies

 

If your not using Linux theres a ton of how-to's/tutorials/documentation  everywhere including tp-link website    

 

https://www.tp-link.com/in/support/faq/3448/

 

goodluck