Internet Bandwidth issue


We have been noticing that Internet Speed of some end-users is reducing drastically post installing Zscaler Client Connectors.

If the ISP speed is 100 MBPS, user is getting just around 2-5 MBPS when performing a speedtest.

If we remove the ZCC from the system, then again Internet speed is normal (80-100 MBPS).

Noticed that this is happening only for some Random users.

Can some one share any thoughts on this?

Rahul V

Hey Rahul,

sounds very familiar for me. If you use Tunnel 2.0 please check ZTunnel 2.0, DTLS/TLS, MTU and ZTunnel 2.0 DTLS and Vodafone Cable.
Since we set our configuration as documented things got way better.


1 Like

Hello Manuel,

We are using Tunnel 1.0.

Rahul V

Some speed tests out there are not proxy aware so they give out misleading data. Please see Measuring the Performance of the Zscaler Service | Zscaler.

You can also use the following for more accurate results:



Hello Richard,

At least we need to get 60-70 % of expected speed in speedtest results.
We are not even getting 10% of the ISP Speed when we do the test.


Hi Rahul,

2 things to try as a simple test and apologies if you have.

  1. Direct cable to internet router (rule out wi-fi, homeplugs, wi-fi extenders)
  2. For s single user, ask them to disable IPV6 on the home router and not the laptop then test again

I’ll explain more if this improves the user experience