Hopefully this helps you. But for us...

NOT using 5g wifi connection fixed FTP- and other issues- for us. Try 2.4 g instead.

5g is temperamental our experience. Maybe it's all the wireless stuff we have in and around our home and neighborhood that's causing issues... But, we've had experiences with other wireless devices gacking out or choking too (or just stopping working wirelessly), like iPhone, on 5g connections.

More info, for me:

I tried to set up FTP and it wouldn't work Then, struggling with it, suddenly it did work. Wat...? uh.. ok... Then, it frustratingly suddenly didn't, for an unknown reason. Pi was wiped (for another reason). Then, there was no FTP success for me at all.

And in my struggles after the wipe...

I could ping the Pi from other machines I could SSH into the Pi using its IP address from the Pi itself (ie: 192.160.1.95, or whatever). And I could SSH into 127.0.0.1 from the Pi itself (so SSH worked fine) I added extra FTP ports, just in case (sudo nano /etc/ssh/sshd_config), even odd/high ones just in case (like 44444). And yeah, I restarted ssh process server after the changes. No luck. I checked firewall to make sure nothing else was getting in the way. Then, peak ANGER: my husband could FTP to the pi, but I still couldn't!!! Not with Filezilla, and not with SublimeText SFTP, not with anything. No dice.

Then, out of the blue randomly, he complained that the 5g connection dropped on another unrelated device. That's when I checked my Pi, and there it was, "5G". On our wireless router we have 2 access points: one for 5g, and one for 2.4g. I then switched away from 5g for my connection, over to the 2.4g one instead, and instantly it worked!!

Also, just now as we're literally debugging the whole situation still this very moment, diddling around with 5g vs 2.4g, he told me that when he uses 5g on his Pi (we have two - he has one and i have one), his laptop's connection, which is also on 5g, totally fails and locks up.

Anyway, 5g and the Pi seem to be bad combination... at least that's what we've concluded so far in our efforts.

So, that's our story.

Can't see files in retropie