Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

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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. 

Aswin_mk's avatar
Aswin_mk
Icon for MVP rankMVP
Dec 24, 2025

Hi,

Did you check the CPU,RAM required for new modules (vCPU,RAM).

 

BR
Aswin

  • tjoll66's avatar
    tjoll66
    Icon for Altocumulus rankAltocumulus
    Dec 26, 2025

    Hi, 

    CPU and RAM seems to be okay. I've got 8vcpu's and 64GB of ram. I would be surprised if the F5 needs more for only 1 vip in a lab environment with about no traffic passing. I did check some memory related logs like OOM but I could not find any.