Your ISP is blocking UDP traffic and that is why the client is failing. Looking at your debug logs, your connection is successful during tcp session but fails when the secret is transmitted during the udp session. They are probably using udp for performance reasons but the client should be able to switch to tcp only. Wish they had a simple toggle switch that would allow tcp traffic only to work around situations like yours.
Happy Holidays

Hi everyone, I've a Kerio Control (update at last release 9.3.2. build 3557) and VPN service correctly configured no problema in connecting from remote but from 2-3 days I can't connect witch VPN, i get error "udp traffic is probably blocked". I've try from different location and with differente PC but nothing. I don't changed nothing in Kerio Control on in our office but VPN stop working some days ago.
From the log I view user logging in VPN but 10 seconds later peer closed connection.

Any ideas??

Thank you in advance.

billybob wrote on Tue, 24 December 2019 12:34

Your ISP is blocking UDP traffic and that is why the client is failing. Looking at your debug logs, your connection is successful during tcp session but fails when the secret is transmitted during the udp session. They are probably using udp for performance reasons but the client should be able to switch to tcp only. Wish they had a simple toggle switch that would allow tcp traffic only to work around situations like yours.
Happy Holidays

by THEY do you mean Kerio or my ISP?

Again, my ISP claims they are not blocking any ports.

thanks

can anyone clarify which ports Kerio uses for VPN? Certainly 8080 and 4090, but are there any others?

thanks!

Hello,

I'm having the same issue as yours, were you able to find the solution for this?

it will be a great help.

Thanks