Client's machine freezes up on backup start, server shows infinite indexing

I’m running urbackup client (Debian) and server(Ubuntu) in local network. Server detects client and starting full file backup of /var, /etc and /home directories setted as default. After few seconds of backup process start client machine freezes up, server showing “indexing” and nothing changes for hours. Even after forced stopping of backup process on server, client doesn’t recover or responding. A dattobd kernel module is installed on client. After beginning of backup in client’s root directory appears datto snapshot (so i suppose datto is working). Also was a try on Debian client installed on virtual machine using EXT4 filesystem with same behavior.

Client configuration and installations:
OS: Debian 9.13
Kernel: Linux 4.9.0-15-amd64
Filesystem: EXT3
Snapshot mechanism: dattobd v.0.10.15
Urbackup client: 2.4.11 (with auto-update)

Server configuration and installations:
OS: Ubuntu 18.04.3 LTS
Urbackup server: v2.4.13.0

Client logs: urbackupclient.log (187.6 KB)
Server logs: urbackup.log (16.9 KB)

From the client log:

2021-04-19 16:04:32: Creating shadowcopy of "var" in indexDirs()
2021-04-19 16:04:42: ClientService cmd: #IS2ylSXBzW0vtoNBTMEAy#2PING RUNNING pc_done=&eta_ms=61000&status_id=1&speed_bpms=0&total_bytes=-1&done_bytes=0&paused_fb=1#token=QuPxOkq4xflNpuZLONSO
2021-04-19 16:14:55: SQLite: recovered 766 frames from WAL file /usr/local/var/urbackup/backup_client.db-wal code: 283

Seems the client was restarted after 10min… Maybe it hangs when creating snapshots. Looking at if the snapshot script is running should give an answer. Maybe you stoped it? Can’t tell more from the log.

So, if machine was freezed, how can I watch snapshot script is running? Btw, server logs that he can’t get file list from client.
UPD. The last command urbackupclientbackend process executes before client’s machine freezes up is in datto_remove_filesystem_snapshot script.

Read that only the indexing freezes…

If the whole machine freezes it is likely a Linux/dattobd issue and would be the place to report it…