Internet Speed is Very Slow when ZCC Connected in Home Network

  • We are using Tunnel Ver 1.0
  • ZCC Connected Speed drop from 100Mbps to 1Mbps
  • System Restarted Without Zscaler No issue
  • System Restart with Zscaler works fine 10-15 min then Speen goes to 1 Mbps
  • Try to identify using ZDX by nothing happen
  • Try with help of Zscaler TAC no resolution till now
  • System IPv6 disbaled
    If anyone has any idea please share we will try to do that.

Hi Hriday, please work with your Zscaler account team. They can escalate within support to help find a resolution.


Thanks kb, yes, working for the last 2-3 months, but no proper resolution
User complaining every day, If anyone has the same scenario and resolution on their tenet that would be helpful
We have premium support with Zscaler

Hi Hriday,

if you turn off ZCC IA when the speed drops down to 1Mps - does that resolve the issue?


Hi Manuel,
Thanks for your reply.
Even if we disabled ZIA, the scenario does not change during the same session, once we restart and ZIA is disabled it works perfectly.

Hi Hriday,

Apologies for the back to basics questions:

  1. Home user tried a LAN cable rather than Wi-Fi ? (to avoid wifi mesh complications etc)
  2. Tethered to mobile phone and tested ? (Removes complications of router AV security or ISP inspection module)
  3. Tunnel Driver Type - Route or Packet driver based ? (sounds route based)
  4. OS version ?
  5. ZCC version ?


I see the same issue. I have tried multiple versions of Tunnel 1.0 and Tunnel 2.0, TLS/DTLS modifying MTU but my bandwidth drops significantly when ZIA is on. If I turn it off I get better speeds. I know I won’t get my full bandwidth but it’s definitely something noticeable.

I have tried the wired directly to the ISP Router/Modem with the pretty much the same results. I’m going back through and rebuilding everything making sure I didn’t mess up a configuration and will check back in if I come across something.

1 Like

I am also facing the same issue, no resolution from TAC on low speed issue.
We are using V2.0 DTLS. Some users are getting 0.1 mbps speed when they are on DTLS…
However we have moved some users on V2.0 TLS they are getting actual speed.
Might be some ISPs are blocking DTLS from their end.
This is my observation, don’t know whether I am right or wrong.

I have heard that same thing about ISPs not liking the udp/443 for dtls. I’ll give a shot again and do some more testing.

Any ideas why an ISP would be throttling DTLS?

Thanks for your query please find the reply,I hope you have a solution

Hi Hriday,

  1. Okay so wifi only, do you see constant flips between 2.4 to 5G for any of these home users ?
  2. Silly one, latest supported Wi-Fi drivers for win 10 ?
  3. Packet filter, strange that a system restart is required before you see better performance. ZCC service restart doesnt give you the same result ?
  4. What are you using for system management SCCM, Intune etc ? (thinking about the 15 minutes of good performance before it degrades the TLS tunnel)
  5. ZCC x64 - Nice ! All AV bypasses or process Whitelisting done along with windows Firewall exceptions ?
  6. Does any of your home users have a fast ZCC experience ?

Sorry for all the tedious questions

Working with Sr. TAC Engineering and will post any updates I get.