Early versions of LapLink
Requirement - For Laplink transfer
If you are planning to transfer Laplink from one computer to another via the Laplink cable, note that only the serial version of the Laplink cable can be used for that.
Problem #1 - Similar speed
A problem sometimes seen, is DOS versions of Laplink requiring the use of computers running at a similar speed/performance. For example, if I connect my 6 MHz IBM 5170 up to my 486DX-66 clone (via serial or parallel Laplink cable) and start transferring files, I find that after about a minute, Laplink goes into perpetual 'timeout' (continually displays 'timeout'). If I then switch the 486DX-66 out of turbo (goes to 8 MHz), then restart Laplink at both ends, all goes well.
Others on the Vintage Computer Forums have seen the same problem.
Problem #2 - Version incompatibility
I can not get different versions of Laplink to communicate at all. So for example, I can not get Laplink 3 to communicate with Laplink 4, and I can not get Laplink 4 to communicate with Laplink 7.5 (for Windows 95). It is as though the authors have made changes to the transfer protocol at each version, dropping support for the earlier protocol.
DOS version of Laplink running in DOSBox on a modern computer
Laplink 3 can run in DOSBox, but I would not describe my experience of that as 'stable'. For what it's worth, the procedure is at here.
In my experience, a better solution to the above is the use of FastLynx 3.3, although, like the above, anticipate a possible problem if you intend to use a USB-to-serial adapter. The procedure is at here.