Network Congestion Fault Diagnosis (1)

A few days ago, I debugged the network for a new office building in Branch C and passed the test. Network Architecture 1.

 
Network Architecture

Just a few days later, the Network Manager of the C branch came to the phone and said that all workstations could not be mounted. Why did the system suddenly fail to access the Internet when the debugging was done well? If I couldn't understand it, I had to comfort him first and promise to go to the site to handle the problem immediately.
Ping the gateway of their CIDR block on the local machine and ping xxx. xxx.117.253-t. The remote connection fails, and other factory branches also use the CIDR Block 117. Then ping the 2810 switch on the office building of branch A with the routing function and VLAN division.) ping xxx. xxx. xxx.233-t, normal. It seems that the cause of the fault can only be searched from 2810. The Network Architecture of CIDR Block 117 is shown in.

 
Network Segment Architecture