For a while I have a set-up running a Mathematica front-end on a Macbook and a remote kernel on a Linux (CentOS) computer. Recently something changed and I have issues with the remote kernel but I cannot pinpoint it. I upgraded MacOS to 10.12.4 and also Mathematica to 11.1 on both systems.
When I start the remote kernel, I get the following message :
LinkConnect::linkc: Unable to connect to LinkObject[email@example.com,firstname.lastname@example.org,56,2].
LinkConnect::linkc: Unable to connect to LinkObject[email@example.com,firstname.lastname@example.org,57,3].
LinkObject::linkn: Argument LinkObject[email@example.com,firstname.lastname@example.org,57,3] in MathLink
PrivatePreContextSwitchOut] has an invalid LinkObject number; the link may be closed.
At first everything seems to work. I can do computations and plot graphics. However, any dynamic or interactive (e.g. Manipulate) command fails. So I presume the failed link is used for this.
The Macbook is effectively listening to the ports as can be seen from the output of lsof :
java 2987 peterb 62u IPv4 0xdbd5c28e4af9a547 0t0 TCP macbook-pro.sky.lan:53743 (LISTEN) java 2987 peterb 63u IPv4 0xdbd5c28e519a1357 0t0 TCP macbook-pro.sky.lan:53744 (LISTEN) java 2987 peterb 64u IPv4 0xdbd5c28e5176186f 0t0 TCP macbook-pro.sky.lan:53745 (LISTEN) java 2987 peterb 146u IPv4 0xdbd5c28e46850a5f 0t0 TCP macbook-pro.sky.lan:53746 (LISTEN)
A port scan of the Macbook done on the Linux computer confirms that the ports are open. So I does not seem to be a network or firewall issue.
So I am stuck now and out of ideas where to look (not really an expert in these link issues).