Windows causing Bandwidth / Network issues

[NathanH99]

Hi,

 

I am a network manager inside a trust of three secondary schools and multiple primary schools.

 

On the 11th of March 2025 we started to experience some network issues at all three secondary schools and potentially primary schools. Over the last few weeks we have been investigating the issue and so far have found out the following

 

• The network issues happen when at least a room of 32 computers are being signed into at the same time however more that sign in worst the issues are... therefore we see the network issues at most lesson starts.
• The cause of the network issues is from the site deploy.static.akamaitechnologies.com, which from research is a content delivery site for many companies including Microsoft. On sign in to a computer this site is sending roughly 30/40mb to each machine that is being signed into resulting in the network crashing for around 10 minutes, speed tests come back at around 10Mbps and the LAN comes to a halt.
• When looking at the App History in task manager "SVCHOST" is roughly using 600Mbs of network per sign in.
• When looking at Data usage for the past 30 days, system is using a lot of data usually around 40Gb or 10Gb a week.
• We have recently discovered that this does not happen to accounts which are not federated with azure and are local AD only. We have tested this many times and the results come back the same each time.

 

The current theory is it is something that is downloading / updating during the sign in of a azure federated account as we use single sign on. So far the following actions have been done however no progress has been made.

 

• Windows store apps have had there automatic updates disabled.
• Windows updates have been disabled
• Microsoft Teams has been uninstalled
• OneDrive has been disabled
• Delivery Optimisations have been setup to the Microsoft standard.

 

Does anyone have any idea what this could be? What we can try next? Any software to track down the culprit? Any advice is massively appreciated!

 

Thanks in advance,

 

Nathan

 

Screenshot of Realtime smooth wall logs

 

 

Extra Info about one of the Schools

 

Internet line - 1Gbps up and down leased connection (Ruled out due to each school having different ISP)

Switches - Unifi Pro switches with a 40Gb backbone (Rules out due to each school having different Switches)

Firewall - Smoothwall S9

Computer count - 1000 roughly

 

[milesla]

Hi

 

Have you tried putting an exception rule in on your smoothwall.  If it's generating that much traffic i suspect the smoothwall is "having a time" with it.  Additionally, are you using caching with your smoothwall.  At 1Gb connection speeds this should really be turned off.  

 

Finally, what is your AV solution doing, again exempting deploy.static.akamaitechnologies.com may help.

 

goodluck