Tuya Zigbee WiFi gateway loses connectivity after several months of use

Hello.
Has any user had a problem with their Tuya Zigbee gateway intermittently losing connectivity with their devices?
I had a wifi gateway that stopped communicating with devices after about six months. Supposedly rebooting the router and unplugging it helped, but it was terribly annoying.
I bought a new one, paired it up and it worked again for
about six months, maybe more. Now it likes to lose connection and behaves like the previous one.
The power supply is sufficient, it is b. close to the router( it doesn't really matter). I have no idea what to do with it
to do with it, as the house has 20 elements and it should be "almost" reliable.
Should I buy a third gateway on the network cable?
How do I solve the problem without completely changing the system?

And does this gateway communicate with devices over wifi?
To wifi they will connect themselves, It rather "mediates" the communication with BT.
If it loses devices then the problem is not with the lan network....
Greetings. J.

I assume she has a wifi problem, because all the zigbee goes down at the same time and she is also offline at the time

And how do you connect the gateway to the router - fixed IP or dhcp?
A hint from big brother
Although the default IP lease time is usually 24 hours, some routers allow you to set very long terms. If the gateway cannot properly renew the address when the 'lease' expires, it loses connection to the network.

Or maybe you have some sort of restriction on your router - login time - maybe you need to implement an auto reset in your router every 7 days for example....
Greetings. J.

DHCP. I will try setting it to static.

It is a pity that we will find out the results in six months....
Regards. J.

A hasty conclusion.I emphasise: 2 instances of proper functioning and after a contractual period of six months a sneeze.
Hence the question about the reasons for this state.
I didn't get any clues beyond a fixed IP, so I did a brute-force treatment: gateway reset and painstakingly adding 26 devices scattered around the house:-(