Owncloud client gets stuck on "Waiting..." status

Hello everyone.

Expected behaviour

Cyclic automatic synchronization

Actual behaviour

Client get stuck on “Waiting…” status. This happens 1-3 times a day. I need to logout of the client and start it again manually.

Steps to reproduce

  1. Just waiting problem… No dependencies detected when it appears.

Server configuration

Operating system: Ubuntu 18.04.5 LTS

Web server: Apache/2.4.29

Database: 10.1.47-MariaDB

PHP version: PHP 7.2.24

ownCloud version: ownCloud 10.6.0 (stable)

Storage backend (external storage): -

Client configuration

Client version: 2.7.6.3261.x64

Operating system: Windows 10 and Windows 2016 Server tried and tested

OS language: English and Russian tried and tested

Installation path of client: C:\Program Files\ownCloud

Logs

  1. Client logfile: I think the problem appear when happend this:
02-18 19:07:40:018 [ info gui.folder.manager ]: Scheduling folder "1" because it has been 7200050 ms  since the last sync
02-18 19:07:40:018 [ info gui.folder.manager ]: Schedule folder  "1"  to sync!
02-18 19:07:40:018 [ info gui.folder.manager ]: Sync for folder  "1"  already scheduled, do not enqueue!
02-18 19:07:45:018 [ info gui.folder.manager ]: Scheduling folder "1" because it has been 7205050 ms  since the last sync
02-18 19:07:45:018 [ info gui.folder.manager ]: Schedule folder  "1"  to sync!
02-18 19:07:45:018 [ info gui.folder.manager ]: Sync for folder  "1"  already scheduled, do not enqueue!```

2. Web server error log: no errors

3. Server logfile: ownCloud log (data/owncloud.log): The same as client:

```02-18 19:07:40:018 [ info gui.folder.manager ]: Scheduling folder "1" because it has been 7200050 ms  since the last sync
02-18 19:07:40:018 [ info gui.folder.manager ]: Schedule folder  "1"  to sync!
02-18 19:07:40:018 [ info gui.folder.manager ]: Sync for folder  "1"  already scheduled, do not enqueue!
02-18 19:07:45:018 [ info gui.folder.manager ]: Scheduling folder "1" because it has been 7205050 ms  since the last sync
02-18 19:07:45:018 [ info gui.folder.manager ]: Schedule folder  "1"  to sync!
02-18 19:07:45:018 [ info gui.folder.manager ]: Sync for folder  "1"  already scheduled, do not enqueue!```

My Owncloud server and client in local net. Server has a good SSL certificate from Sectigo.