Issue with FTP over hostapd hotspot and specifically an Android client using ProFTPD

So I have been using this setup with an iPhone quite successfully. The "server" box is running Fedora 34, on which is installed ProFTPD. I went through and configured through the visual client the firewalld zone to allow the FTP service through, I even disabled the firewall to check. I have an Android phone which is a tad aged. It's using Android version 5.1. I try to connect via an Android client and via the Chrome browser in the usual manner. Now, on my server machine, I opened up Wireshark and watched the hotspot interface. Sure enough, ARP hits "Who is 192.168.x.x", no problem, reports the correct MAC and IP addresses. The FTP request is visible. Even pinging the device from the server works. But for some reason, no response is being sent back from the server, and it's not because it's blocked. The connection just times out. I note that this only seems to be happening when I use this Android phone, it's a ghost in the shell scenario for sure. I'm going to try a different phone, shouldn't matter right? Makes no sense that it should matter! The local login of the server still works and there are no options regarding bind address, so I cannot assume it's that.