AirPort Extreme error reading specific files from disk share

Mostly any portable drive over 2TB uses SMR format on the disk.

This might lead to the problems you listed although it is not something I have seen. It is the only way I can put together the evidence that you have issues on Airport but not when shared via SMB protocol on a computer. In that case the computer has superior disk management and is a lot more architecture aware cf the firmware of the airport.

Read up what SMR does.

https://www.storagereview.com/what_is_shingled_magnetic_recording_smr/

In general it is advised to NOT USE SMR DISKS in any NAS or Router share device. They are known to cause trouble. SMR drives are ok for bulk backup when directly connected to a computer but don't use them in a file sharing type setup. Once you start to write over tracks the speeds will become terrible due to need to record and write all data in a sector.

NOTE.. drive manufactures are pretty sly about telling the truth. SMR drives are common in Portable drives over 2TB and desktop drives of 4TB when those drives are used in USB storage.

tchubees wrote:

The external My Passport 4TB HD AFS formatted works perfectly when connected to Mac. However, when sharing it via AirPort Extreme, I can't open some of the files. And when opening some of the video files with errors, they sometimes starts playing part of the video from other files in the same disk.

Just to make sure I understand your post. By "AFS formatted" are you referring to Apple's APFS format? If so, then a drive formatted as such, cannot be shared out when connected to an AirPort Extreme or Time Capsule base station. It must be formatted as HFS+ to work in this manner.

Ref: Using a USB drive with an AirPort base station - Apple Support

Then the issue may be that the base station's USB port it too underpowered to handle your external USB drive. This does show up with the symptoms that you describe. The WD My Passport drives typically are bus-powered. If this is the case for yours, then this could be the culprit.

FWIW, I have a number of these drives and I really like them ... but, I did have issues using them with the AirPort base stations. In my case, they would cause the base station itself to "drop off the network" periodically. When I removed the drive the drop-offs stopped.