MATLAB and SimuLink take a very long time to load or be ready

I have MATLAB R2019b installed locally in my $HOME directory on CentOS 7.6, using a corporate license (with the network.lic file stored locally). MATLAB starts up quickly (~5s), but takes a long time to be ready before I can do anything. For example, after clicking on the Simulink button from the main toolbar, it takes at least five minutes before Simulink actually loads. Once it is loaded, if I go to the Simulink Onramp program to pick up where I left off, it opens the main window quickly enough, but then takes another five minutes or so to load the Tips and Objectives panes. This happens every time I start a new task.

Additionally, I am connected to my home WiFi, then to my company's network via a Pulse Secure VPN. I also have a corporate proxy that my internet traffic goes through.

I have already tried several different methods to speed this up, including setting the MLM_LICENSE_FILE environment variable, pointing at the local network.lic file; starting MATLAB with the matlab -c <path/to/license/file.lic> command; trying various proxy settings within MATLAB > Preferences > Web (I have tried with no proxy to see if it uses my system proxy settings, two different proxy servers, with/without authentication); making sure Toolbox path cache is enabled, no source control is used; and even resetting my preferences by removing the .matlab directory. Nothing has worked so far, and I'm out of ideas.

Anyone know if this is fixable and what I might do to speed things up?

Thanks in advance!

[Walter Roberson]

Is your network server specified by IP or by name? If it is specified by name, then insert the IP address for that name into your /etc/hosts so that there is no need to do DNS.

[Bryan Avis]

Are you referring to the network servers listed in the network.lic file? There are three network servers there listed by name. I have added them and their corresponding IP addresses to my /etc/hosts file, but this doesn't seem to have changed anything. I also tried directly replacing the names in the network.lic file with their IP addresses, but that didn't do anything either.

[Walter Roberson]

It might be worth checking to see if all three are reachable. The order used is the order from the file, with it being necessary to time out before the next is used.

This would, however, only affect the initial launch, not for example the TIps and Objectives once you had Simulink running.

If I recall correctly, Tips, and Documentation, run in a different process that is communicated with using TCP, and that communication can be interfered with by firewalls and proxies. It would probably be worth tossing in a network monitor such as wireshark to see if there are requests going out that are not being answered promptly.

[Bryan Avis]

All three appear to be reachable via ping, so it appears that MATLAB is successfully retrieving the license on startup. However, after running Wireshark and monitoring my network adapter's connections, with only MATLAB running, I see a lot of ESP protocol requests from my computer to what appears to be a company VPN address. When I ping this address, it times out every time. I'm not as well-versed in network protocols, so I'm not sure if this is normal operation or not.

[Walter Roberson]

It is not uncommon for firewalls running ESP to not be reachable by ping. If you are getting prompt response to the outgoing ESP packets, then the firewall (VPN) is probably running as it should be. If you have outgoing ESP packets but no corresponding ESP packets then you might have a VPN issue.