I'm the STM32F207 user, as title mentioned, I have a trouble when configure the usb packet size from the default 64 bytes to 256 bytes. The problem is that my usb device may not be able to connect with all PC host(there are about 10 PC with different version Windows for test) when I configured it as 256 bytes for bulk in/out endpoints, it's strange that my usb device couldn't connect with two PC host which were not properly installed the usb driver for my usb device, but it just worked fine on all other PC hosts, and If I configured my usb device with 64 bytes packet size, it worked fine on all PC host.
The issue was happened during the USB initialization, as PC host will request the Device Descriptor, Configuration Descriptor etc..., when PC is requesting to Set Configuration Descriptor, my usb device was received that request and set the configurations accordingly and then respond a "Zero Length Packet" as the ACK packet to the Host, but after this ACK packet was issued, PC host stopped to request the last Configuration Descriptors.
I've no idea to keep debugging with issue, any suggestions are appreciate.
attached are some related images from my debugging: