USG Flex 500H - Problems with Services that require authentification

Niklas_Lauf

We have a new USG Flex 500H.

It is set up as firewall and gateway, connected via a known to be stable modem on a stable 1GBit/s fiber optic line.

With the new firewall we now have issues with some services like Outlook, Teams and Jira (Atlassian) where they randomly will no longer load/authentification will fail.

On the firewall we only use the default security policy control rules.

For debugging purposes I have turned of all security services. The issue persists.

In the log (debug) we see a lot of packages from Microsoft servers dropped with the message: "invalid state detected DROP". Connections are usually to ports above 5000 but a lot are also to port 443.

PeterUK

Have you disabled DoS Prevention

Niklas_Lauf

https://community.zyxel.com/en/discussion/comment/68803#Comment_68803

Yes I have, as I said, everything is turned of except policy control.

Zyxel_Melen

Hi @Niklas_Lauf,

May I know if your firmware version is the latest version? Could you provide the diagnostic info for me to check? I will DM you for the request.

bbp

https://community.zyxel.com/en/discussion/comment/68815#Comment_68815

A long shot, but is DoS Prevention loging enabled in "Log & Report → Log Settings → Log Category Settings" under "Security"?

Zyxel_Melen

Hi @bbp,

You can enable logging in Security Policy > DoS Prevention > Profile > each profile. You may reference the screenshot below:

bbp

Hi @Zyxel_Melen

You can also disable/enable what get logged in "Log Settings"