No Gigabit ethernet on 2009 iMac

[zsemberi]

Hi Everyone,

I am new here but with a same old problem...
I read other posts about this problem/topic, but I couldn't find a solution. My ISP is giving me 1000 G net, but on the speedtest it doesn't go above 100. I changed my ethernet manually to 1000baseT, but then said cable is not found or not good. The cable is brand new from ISP guy, cat5(e).

How can I fix this problem. Also I would like to use internet via wi-fi router (gigbait router), but will the Airport Extreme card (Supported PHY Modes: 802.11 a/b/g/n) handle speed above 100?

I called my ISP they came with a windows OS based laptop, plugged in the ethernet cable and it basically flew with 700Mbps at least, so the cable is good (CAt5e), my ISP is providing 1000 Mpbs on Win laptops its super working, super fast. I am really upset now, what shall I do, is there something wrong with my setups? Is it a connection that it is not Ethernet setup but PPPOE?

Thanks a lot for any help, advice. I am struggling....

iMaclate 2009, macOS Sierra (10.12.5)

 

[nambuccaheadsau]

Many things to consider. Old iMac, slow processors, how full is the hard drtive, how much memory, any antivirus software installed.

 

[zsemberi]

Great and how to eliminate the problems one by one? Hard Drive is not full, processor is old, iMac is old, 12 Gb RAM, new SSD for the OS AVG Antivirus installed, though even cable plugged in my TP-Link router seems like the built-in Wifi card is not letting anything through above 100 Mbps.

 

[Significant1]

Turn off Wifi on your machine to make sure you are connected through ethernet. Your previous picture frem network settings with Ethernet yellow and self-assigned ip-address seems wrong, but I have no experience with PPPOE. Does your ISP require that?

Also make sure your ethernet-port is clean and all connectors intact.

I wonder if you can test from recovery (is safari possible..), to eliminate any software you might have installed. If you have Windows installed on a bootcamp partition, you could try that, since you say it is working on windows.

 

[zsemberi]

yes they allow pppoe settings only, connector is clean and intact

 

[verdejt]

The difference between 100 baseT and 1000baseT is pins 4&5 and 7&8. These pairs are only used in gigabit. I have seen brand new cables have less than shall we say great connectors. If the cable you are using worked on a windows machine it really isn't eliminating the jack or the cable. The jacks are a little different from manufacturer to manufacturer. I would recommend a cat 5 cable tester and check the cable to make sure there are no intermittently loose connections. While under test wiggle the cable about at the connectors and verify all 8 wires stay connected. If so then maybe take a good look at your jack and make sure none of the pins are out of alignment or pushed down where they don't make contact. Since 2007 iMacs have been gigabit so being an older iMac has nothing to do with it. Next would be to make sure the jack you are plugging into is actually gigabit. I have had top of the line routers where all they had was 100baseT or only 1 gigabit connection. If you have a gigabit switch handy try plugging your iMac into that and see if it negotiates and indicates gigabit. Don't assume all routers or provider equipment is gigabit. Like I said my top of the line Verizon router was only Ethernet (100 baseT).
[doublepost=1509233212][/doublepost]Also just because you might have a 100g connection this is bandwidth not necessarily a gigabit connection. Read your modem/router's documentation to verify that the ports are gigabit.