serial port freeze

[COLLAUDIN]

hello, I work with a PC under w10 (20H2) and a virtual image in OS/2 WARP. when I'm in version 5.2.44 the series communication between OS2 and my automaton works fine (full load without worries loading time about 10 minutes). when I migrate to version 6 (all versions), the communication no longer works (doesn't start at all or hangs after a while). if I go back to version 5, it works again. what I see is that the transfer speed is much faster as if it did not take into account the transfer speed. can you tell me what to do to make it work in version 6. Thank you