How to resolve network conflict between mobile phone and laptops?

Question

Computer networks

Small business network:

• Cisco 1811 primary gateway gateway for all devices on the network and vpn with other branches
  
• DHCP + DC Windows server 2016
  
• Zuxel 24 ports managed for servers and other critical equipment
  
• No name 24 ports for everything else
  
• 2 more no name 8 ports poe for ip cameras
  
• Another dozen 5 port switches where there are not enough laid outlets
  
• WiFi 2 access points and 3 WiFi routers from different manufacturers, everything in AP mode is not distributed by anyone except DC ip, carved ssid everywhere
  

The essence of the problem:
From time to time there were complaints from users with laptops that they had problems with WiFi (some did not receive an IP, while others did not reach anywhere). During the diagnostics (which took a lot of time), it was revealed that in their ARP table opposite the ip address of the main gateway there was a MAC address not Cisco 1811 but another. MAC addresses are different for all devices on the network.. Having broken through the database of poppies, it was revealed that this is the mobile phone of one of the employees (Huawei). As soon as you turn off WiFi on this mobile phone, the problems on the laptops disappear. Through observations, it was revealed that the problem manifests itself if the laptop connects to the network after the phone, if the laptop has already connected and received ip and the correct arp, the problem does not appear even if the phone is also connected to WiFi. I also want to note that the problem appears even if the laptop and phone are connected to different APs with different SSIDs.
What was done:
It was decided to clean up the network equipment. Several APs and mikrotik routers were bought and seamless WiFi was built using CAPsMan technology. I also bought a Cisco SG220-50 switch. The network was divided into vlans common and for mobile phones. 2 ssid for laptops with access to servers and mobile phones with internet access only. On the Cisco 1811, a new interface (gateway for mobile phones) was raised with access denied to all other networks. An additional interface for DHCP on mobile phones was also raised on DC.
Results:
In general, this did not improve the situation and the phone interferes with the laptop, which is located on a different subnet and in a different vlan. Do you have any idea about this?

Answer 1

You need to start with commands on ipconfig /allthe arp -alaptop (as I understand it, Windows is there) and send the result here. This command must be given in two situations: " the laptop connects to the network after the phone " and " the laptop connects to the network before the phone ". And if you compare the results line by line, you will most likely find the source of the error.
To the heap - it would be nice to give a command tracert -d шлюз
In the first approximation - the phone tries to distribute the Internet and "pulls the computers to itself." It may even be trying to be a DHCP server.