Few days ago my router showed that there's a new versin exists (I was on 1.2.2) I updagaded and everything was fine, but I noticed that connectivity is slow, so I checked the spee (speedtest / fast.com) and saw 200Mb/s. Discussed this with provider and they told me that don't see any problem, so I rebooted the router and reboot helped.

So, seems that new firmware version has regression that cause to the router to reduce speed overt the time.

Think twice before installing it.