Lost connection to LMS since update to v7.9.1, 1517314665

There was an update to v7.9.1, 1517314665 pushed to my system on Feb. 09. Since then, I can not mange to access LMS any more from computers connected to the network (through SERVER_NAME:9000 or through my Duet. LMS seems to be running correctly on the server (Windows Server 2016 Essentials), but connectivity seems not to work any more. Tried to stop and restart the server with no effect. Can someone point me to any trick to put my system back on?

Thanks