Limited download speed on a USG Flex 100


I'm contacting you because I have a USG Flex 100 (1st generation, with SFP) at a customer's with which the download speed is limited to ~200/250Mbps (whereas the firewall is supposed to take 900mbps, and 350mbps with UTM services, unless I'm mistaken). No problem with uploads (I'm up to around 580Mbps, which is more or less in line with the Internet connection's capabilities).

I've tried a factory reset, but it doesn't make any difference. Even with the UTM services, Policy Control and ADP turned off (All USG Flex services are turned off, basically), the DL remains at ~200/250Mbps.

More surprisingly, I have two other USG Flex 100s (also 1st generation with SFP) at two other customers, with similar configurations, and there, on the other hand, I have my 360Mbps (with IDP, anti-malware and content/DNS filter enabled), and even more on one of them.

I've also noticed that when I do a speedtest, the processor on the problematic USG Flex 100 doesn't exceed 60/65% utilization, whereas on the other two that work well, the processor climbs to over 90% without any problem.

All three USG Flex 100 are on the same firmware (the latest: V5.37(ABUH.0)).

Could this be a hardware problem?

Or might someone have a lead to explore on the software side?...

Thanks in advance for your help!


PS: Sorry for my English, I don't speak it very well, so I use a translator to help me...

All Replies

  • PeterUK
    PeterUK Posts: 3,003 ✭✭✭✭✭
    Community MVP First Anniversary 10 Comments Friend Collector
    edited November 2023

    Are you able to take the WAN MAC from Flex put it on a PC NIC and test the speed without the flex to the modem?

  • David_ECA

    I understand the approach, but that's not where the problem lies:
    I forgot to specify one point: It doesn't depend on the internet connection. I was able to reproduce the problem on two different internet accesses (different locations, modems and operators).

  • Zyxel_James
    Zyxel_James Posts: 663  Zyxel Employee
    First Anniversary 10 Comments Friend Collector First Answer

    Hello @David_ECA
    I would like to know what kind of testing tool/application you test. If you run the speed test with single session, the throughput would be a little bit lower than the datasheet speed.
    Could you provide more information about your test, and also the configuration for testing?

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