Forum Discussion

tjoll66's avatar
tjoll66
Icon for Altocumulus rankAltocumulus
Dec 23, 2025
Solved

VIP is not responding on SYN after enabling other modules like ASM, APM and AFM.

Hi all, I have an F5 VE running 17.5.1.3 in my lab environment for learning purposes. As back-end I installed the phpauction webpage and all configuration works flawlessly if only the LTM  module ...
application delivery
deployment
  • tjoll66's avatar
    tjoll66
    Feb 13, 2026

    Hi All,

    Let's give a quick update regarding my issue for anybody that runs into the same issue. 

    My license was renewed so I could create a TAC case for my issue. TAC rebuild my system in their lab and found a DB value that was still enabled after deprovisioning AFM. See https://my.f5.com/manage/s/article/K16849 for more information.

    Running the following command solved my issue: # tmsh modify /sys db tm.fw.defaultaction value accept

    I'm still looking for information why I haven't found any log entries regarding this setting/dropped traffic.

    Thanks all for your input. 

Shyy's avatar
Shyy
Icon for Cirrus rankCirrus
Dec 24, 2025

Never heard such a thing,
are we talking about only after provisioning the modules, and right after the VIP stops working?

or when adding an APM policy or ASM policy to the VIP it stops working?

tjoll66's avatar
tjoll66
Icon for Altocumulus rankAltocumulus
Dec 24, 2025

Yes, so when LTM only is enabled the vip works fine. Then after enabling, for example ASM, the vip only responds to icmp but is not responding to my SYN packet. Even when I haven't created and attached a policy yet. The same happens when provisioning APM. In that case I have LTM + APM enabled; same response: icmp works, http doesn't. Also when combining LTM + ASM + APM + AFM. 

I think I played a lot with the configuration for learning purposes of my 401 exam, that something broke under the hood. Today I tried to clone the VM and attach a trial license; same issue. So it's definitely something strange going on under the hood.