Network problems connecting multiple clients from same public ip to my google Compute Engine Instance

Question

We are using a Centos 7 Google Cloud Instance web server, and I'm experiencing connectivity problems when multiple clients from my company try to connect to the web server at the same time.

We are surfing the site ok, then suddenly can't connect for a while (perhaps some 10 or 20 seconds, and then we can connect again.

At the same moment, I can browse it perfectly from other ip public from the same subnet and company, other cellphones with 4g, etc. It seems thats some DDOS filter, waf protection, ips signature is doing something. The server only have apache and nothing else.

Is my diagnosis on the right track? How can I fix this behaviour?

Answer 1

It would be worth to check any firewall and load balancer for your application server. As you suggesting that you are able to access website from same subnet when it is inaccessible, can you perform port scanning to review http service and latency through nmap command: nmap -p 80 [public IP address] from external network? It is worth to perform VM instance health checks (CPU load, network I/O performance etc.) during the time website becomes inaccessible. There might be chances that some resources becomes unavailable during high load.