"Another device is using this computer's IP address""Shared" user's slowing down Wifi

[mnya]

I'm using a communal Wif on my Mac, and under "Shared" on Finder, another user's Mac is showing. I also get a message saying "Another device is using this computer's IP address."
Every time the "Shared" device shows up there, the Wifi becomes very sluggish and I'd have to restart the router over and over, without much improvement.
It used to be every page that was taking forever to load (or never load) when this problem occurs, but now it seems to be only pages that require auto-keychain log-ins that are having problems loading - like Google, Facebook, Amazon (for which my Safari already has log-in info (called keychain if I remember correctly?))
(I didn't have a problem logging in this site, but maybe because it was logged-out already.)
Is this like the user under "Shared" is trying to steal my keychains or something?
It's my landlord's Wifi but he doesn't know who the "Shared" guy is, so he won't do anything about it, although he agrees Wifi got slow after this user started popping up

 

[tampasteve]

Go to System Preferences > Sharing > uncheck all the relevant (probably all) boxes.

Also, make sure internet sharing is off:
System preferences > Sharing > Internet Sharing > make sure nothing is checked and it is off

See if that fixes your issue. But as a side note, depending on the wifi equipment, the speed will only be as fast as the slowest machine using the network. So if you are capable of G speeds but there is someone with an old iBook or something that cannot use anything higher than B speeds then you will also be down to B. But it depends on the wifi equipment....

 

[mnya]

Thanks! Is "Bluetooth Sharing" safe to leave on?
Everything else was off, so I guess maybe the user's machine is super slow like you said