I have a linux machine running Mathematica 4.0 (well suited for older linux machine) which has no monitor and the hope that I can use front end on mac mini running Mathematica 11.3 to work as a front end for the remote 4.0 kernel (note since Sierra, Apple no longer supports X11, and Xorg is a fake X11 that broke real X11 programs). 4.0 kernel's "math" binary has option -mathlink, but not -wstp. I believe they use the same standard (MathLink, if renamed). Mathlink is designed to be architecture independant I think: it communicates over (TCP).

When I connect using either of the below I get failures:

LinkCreate LinkConnect etc. I can manually create a link (using 4.0 kernel) but (11.3 kernel) says it can't connect. I don't think it's a firewall issue - i pretty sure i disabled the fw for testing on the linux machine and that Apple's fw doesn't block what LinkCreate chooses.

ref/menuitem/KernelConfigurationOptions. (here there's wolframssh or ssh, ssh seems to work - but the client opening the connect to launch a remote mathematica closes the connection instead of launching and linking). i've tried many options - i'm at my wit's end guessing what is going on. the documentation isn't sufficient to allow me to guess. (LinkConnect[linkb,TCP], done on mac-mini, shows no error: it shows error on LinkWrite). I did check that Linkxxx works on linux/4.0 kernel on same machine (two 4.0 kernels can talk to each other, yes).

I checked "stack exchange" but that only says what Documentation already says (how to connect 11.3 to 11.3, which is trivial).

Any help appreciated thank. I have read the MM 4.0 book sections on this and worked with Mathlink C program examples, but I'm not an experienced mathlink developer.