Can't upload file from client end; stucked at 0%

Dear support,

I have rocketchat installed manually with the specification below; on the server, I can upload and download file, but on the client, I cannot upload file; it si stuck at 0%. I’ve checked through the forum, but non of the suggestion resolve my challenge. I need your help.
Server Setup Information

Version of Rocket.Chat Server: 2.1.0
Operating System: Linux Ubuntu 18.04 x64
Deployment Method: https://rocket.chat/docs/installation/manual-installation/ubuntu/
Number of Running Instances: 1
DB Replicaset Oplog:
NodeJS Version: v8.11.4
MongoDB Version: 4.0.12
Proxy:
Firewalls involved:

regards
wallex

Hello
This work for me: