I have had trouble with OS4 on my A4000T.
I think mine is relaited to the TCP stack though, I am using ioblixether.device which works just great under 3.9 but the stack crashes after a while. (with ibrowse almost always instantly, amirc lasts up to 20 minutes, Yam after a few minutes)
I have yet to try that many 68k programs and all the little programs included with OS4 run fine. (Excluding internet relaited ones)
I am still looking into whats causing it.
The computer works fine after the internet has crashed, just the net programs are locked solid.
Spec: A4000T 060/50 & 604e/233, Cybervision 64-3d, ioblix + ethernet & Thylacine. booting from SCSI drive attached to CS, DVDRW on motherboard IDE (was on a powerflyer but mehh) along with an SD card reader (for booting 3.9

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