The DHCP client (Debian) cannot find the server (but netinstall was able to go online). How should the network be reconfigured?

Question

linux

The PC connects to the Internet using the ONU Fiber Field.

1. Windows can sometimes not receive a response from DHCP for up to half an hour. You cannot specify an IP statically, in this case the network is completely lost. If done

   ipconfig /release
   ipconfig /renew

   then the interface goes down tightly, the answer from DHCP never comes. You just need to restart the interface.
   
2. Debian netinstall goes online fine and downloads all the required packages. BUT the installed system itself does not see the DHCP server at all. But the statically set IP works until the lease lines expire.
   

ip 10.91.103.13 (never changes)
netmask /24 (255.255.255.0)
gateway 10.91.103.1
DHCP 10.10.10.5 (remarkably, it does not ping)
At the same time, Wireshark showed that no one responds to DHCP Discover, but responds to DHCP Inform 10.10.10.163 DHCP NAK message.
Question 1: what is going on in this network?
Question 2: What needs to be done so that Debian can also access the network normally? Because running Windows to lease an address and then running Linux is not an option.

Answer 1

Try adding the computer's mac address to the server's IP address reservation list.

Answer 2

First, see if the system has detected the network card:
If the output is empty, then try the image with non-free drivers.