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Arp spoofing warnings with GS1920-24 managed switch?

LarsRasLarsRas Posts: 1  Junior Member
edited September 2018 in Questions

I have a USG40, and a few cheap switches. I got hold of an GS1920-24 managed switch which replaced one of the other switches. It is connected to one of the USG40 ports. Shortly after that my network started behave strange, dropouts, missing local network connections, missing internet connection, warnings on my macbook of possible ARP spoofing attacks, which is also shown in the  USG log.
The GS1920-24 had a factory reset, and I only changed admin password, and time settings.
Everything was shutdown/powered off (literally I took the power to the house for 5 minutes to power everything off). This has been done twice.

Still see all the issues above.

As soon as I replace the GS1920-24 with a cheap switch, the problems disappear immediately.

Any ideas what happens here?

br Lars


  • Zyxel_RyanZyxel_Ryan Posts: 6  Zyxel Moderator
    Hello @LarsRas,

    According to your description, I am wondering if there is ip collision in your environment. 
    Due to default IP of USG is and it is same as the one of GS1920, if you did not change IP of GS1920, it is most likely that the IP of USG and GS1920 are same. 
    Thus, your USG and macbook warn you arp snooping.
    Could you have a quick check if USG and GS1920 are using the same IP address? 
    If yes, please change the IP of GS1920 to another IP address. Then the symptom should be resolved. 

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