What type of connection you're using to connect to your ISP - static. dynamic, PPPoE, etc. ? Who's your ISP ? Do you have a modem given by the ISP or just a cable from the wall ?

@Marharepa It could be many things, I am not certain about that, but it's worth checking as part of a troubleshooting. You can approach this also like leaving only switch connected without any...

@bmrk Refer to this thread.

@Marharepa You can test if any of the devices connected to the switch, causing the issue by plugging in them one by one and observing the switch/router behaviour.

@dragonfly201270 If you haven't, try this beta FW to see if that would help. You can revert back to the current FW at any time.

@Shipwreck Possibly, the difference in QoS settings is due to the FW version probably, but with your current settings you should be fine.