cnPilot R190V LAN not working but WiFi is OK

Hello there.
We have deployed many cnPilot in the last 3 years. We used to deploy R190W but recently we switched to R190V because of its SIP feature. We thought this shift will bring positive reviews in the future as people will slowly start using IP phones in their offices.

So, after deploying 5+ R190V we are getting a strange problem. Sometimes the LAN ports are not working but WiFI is OK.
What may be the cause of the problem? Should I try to upgrade or downgrade firmware?
What do you suggest community?

Off topic, what pbx or softswitch are you using to provide telephony service to your customers?

What firmware is on your R190V devices?

Now the VOIP /SIP part is not active at all.

4.4.2-R2 in one router.

I am afraid to update system.

Eth ports are not running at all (they are down) or they are up but traffic is not passing? Maybe wireshark can tell us some additional info?
I checked last few release notes to find something about your issue but no luck.
Maybe you can upgrade one of them to see is there any good regarding your issue.
I believe support will tell you the same thing, 4.4.2 firmware is more than 2 years old.