Debian 10 - can not connect to grpc service (gRPC failed with StatusCode.UNAVAILABLE: failed to connect to all addresses)

I need help to fix this error: gRPC failed with [login to view URL]: failed to connect to all addresses I am trying to set up Tinode ([login to view URL]) messenger on Debian 10 Buster server. I start the messenger, it says 2020/10/26 13:25:28 gRPC/1.28.0 secure server is registered at [localhost:16060] but for some reason when I run a Pyhon command to access messenger's grpc service on localhost, port 16060 python [login to view URL] --login-basic=alice:alice123 I get this error: gRPC failed with [login to view URL]: failed to connect to all addresses. Firewall is disabled. At the same time I see that server is listening on localhost:16060. lsof -i COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME tinode 2894 debian 6u IPv6 28530 0t0 TCP localhost:37128->localhost:mysql (ESTABLISHED) tinode 2894 debian 8u IPv4 29043 0t0 TCP localhost:16060 (LISTEN) tinode 2894 debian 9u IPv6 23509 0t0 TCP *:6060 (LISTEN) Please post real bids if you can fix it. I will not pay more than your bid. And tell me if you can help me to fix it without accessing to my server or you will need to access it.