Can't copy to SMB mounted share through web UI using libsmbphp


I’ve tried two different versions of libsmbphp .8 and .9 with our new CentOS 7.3 server, and while I’m able to mount our Samba shares without issues, every time I tried to move a larger file, > 300 MBs, Nextcloud only copies half of it and then it dies. I haven’t been able to find anything in the logs. Is there anything else I need to configure to get this working? SELinux is disabled.