Download cable speed to G5 and Intel Macbook not the same

Question

Download cable speed to G5 and Intel Macbook not the same

We are using a cable connection and were getting 100 download (10 up) on both the G5 and the MacBook. The internet cable goes into a router and the two computers are connected to the router. Very little fluctuation in the speeds.

Recently our cable company (Smallworld) was taken over by Virgin and the advertised download speed is 152; the MacBook (and my son's iMac) both get a steady 160 down and 12 up, but the G5 struggles to reach 50 down - and yet gets 12 up.

The only thing that has changed is the cable hub (Virgin's supehub).

I don't understand why the G5 is now not managing to get the full download speed.

Any suggestions?

G5 2.7DP 8GB RAM, Mac OS X (10.4.11), also 10.5.8 on 2nd internal drive.

Posted on Dec 3, 2014 11:02 AM

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Answer 1

BDAqua

Level 10

239,225 points

Dec 3, 2014 11:34 AM in response to Shaun Ferguson

Hi Shaun, might try this...

Turn off IPv6:

System Preferences » Network » Ethernet » TCP/IP tab » Configure IPv6

Or whatever Interface you use.

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Answer 2

Dec 4, 2014 4:45 AM in response to BDAqua

Tried your idea.

No joy, I'm afraid.

Cheers

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Answer 3

BDAqua

Level 10

239,225 points

Dec 4, 2014 6:48 PM in response to Shaun Ferguson

I wonder if the new one uses a different MTU?

Different Servers/Routers/Modems may have different MTUs, and that can cause Havoc, here's some guides on that issue...

Setting MTU size is a process of trial-and-error: start with the maximum value of 1500, then reduce the size until the problem goes away. Using one of these values is likely to solve problems caused by MTU size:

• 1500. The largest Ethernet packet size; it is also the default value. This is the typical setting for non-PPPoE, non-VPN connections. The default value for NETGEAR routers, adapters and switches.

• 1492. The size PPPoE prefers.

• 1472. Maximum size to use for pinging. (Bigger packets are fragmented.)

• 1468. The size DHCP prefers.

• 1460. Usable by AOL if you don't have large email attachments, etc.

• 1430. The size VPN and PPTP prefer.

• 1400. Maximum size for AOL DSL.

• 576. Typical value to connect to dial-up ISPs

You can temporarily test by pasting this into Terminal, (will go back to defaults when you reboot)...

sudo ifconfig en1 mtu 1492

Ethernet might be en0... About this Mac>More Info>Network

Can also be done in Network Pref Pane>Ethernet tab for the Interface you're using.

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Answer 4

Dec 5, 2014 11:32 AM in response to BDAqua

I'll have a look at the PPPoE setting. It's not switched on at the moment.

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Answer 5

BDAqua

Level 10

239,225 points

Dec 6, 2014 12:12 PM in response to Shaun Ferguson

You don't need PPPoE, but several Routers use the 1492 byte size, other OSes understand & adjust it automatically.

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