@Nico_cepo, My Citrix admin is telling me they had all sorts of trouble with UDP (the default) and switched to TCP–at least when presenting a Citrix-hosted app to an Azure Virtual Desktop session. While that’s not the same, per se, I wonder if there would be any benefit in testing TCP vs. UDP to see if it has any positive effect. Also, he was wondering if you’ve checked your MTU size as that may yield some insight and warrant making some tweaks there.
https://support.citrix.com/article/CTX231821
Grasping at straws really. Hope this helps. We’re at the front-end of our thin client journey but have a lot of Citrix experience from Windows and Mac clients.