Losing packets using fiber media convert

Hey,

I'm facing a problem using a fiber media converter. When I try to ping the Computer 2, from the computer 1 (image attached) using the command ping with the parameter -l 300 (300 bytes), I have lost packets. The connection are really slow.

Is that problem because I'm using a media converter connect direct to an other media converter ( point to point access ) ?

Any suggestions are greatly appreciated

Thanks