Homeplug problem since having infinity installed

I have a really strange problem that I can't work out, my current set up is as follows:

Room 1: Bt infinity modem > asus n66u router > dlan 500 homeplug
Room 2: dlan 500 home plug > tp link switch > pc

I also have a nas connected to the switch.

wireless internet speeds to my laptop are fine from the router, usually between 40-50mbit,
wireless internal network speeds are also fine e.g. copying a file from my nas (which is going through both home plugs and a switch), usually transfer at around 25MB/s (not a typo, megabytes)

wired internet traffic directly from the router are fine
wired internet traffic from the home plugs is extremely slow, usually around 1-2mbits, now here's the weird part, wired internal network traffic is fine, if i connect a usb stick to my router, i can copy it on the pc at over 10MB/s.

which makes me think the problem is somehow related to the home plugs, but then why do they transfer fine for internal stuff? has anyone come across something like this before?

I have tried resetting the home plugs, tried not using a switch, tried moving home plug sockets, but in the end, it only seems to be internet traffic that is affected, and only when going through the home plugs, I'm completely stumped. any ideas/thoughts/suggestions?

My previous ISP was o2, using the same setup, and never had any troubles hitting my 4 megabit broadband to my pc through the home plugs...

Thanks
Raj.

packet size issue?

but as you said strange

In reply to a post by rajravat:

My previous ISP was o2, using the same setup, and never had any troubles hitting my 4 megabit broadband to my pc through the home plugs...

Did you use the same modem and router with O2?

No the modem/router i used was the one provided by O2 (some form of branded net gear), i'm now using the vdsl open reach modem installed by the engineer and a asus n66u, the home hub 3 they provided had [censored] wireless range, but i also experienced the same issue with it.

Are the homeplugs on different ring mains and, if so, do you have any compact flourescent lamps running?

I had a similar problem with Devolo homeplugs between computers on different ring mains- file transfer was fine in daylight hours, but as soon as a CFL was switched on it went down to dial-up speeds.

So roll on summer

I assume it's because if they're on different rings the signals have to go via the consumer unit, where it meets up with all the other supplies in the house, whereas if they're on the same ring there's a direct(ish) copper connection between them. Or something like that.

I'd guess at an EMC issue between the Homeplug and the BT modem - probably RF energy from the Homeplug getting into the modem via its power supply or via the BT wiring.

The easiest way to test this is to see what happens to the Internet throughput to your wireless laptop whilst simultaneously passing as much internal traffic as possible over the Homeplug link. If the throughput to the laptop drops in this scenario, this suggests I'm correct.


If I'm correct, winding the modem's power cable through a ferrite ring as shown in figure 9.3(a) on this page (with the ring finishing up as close as possible to the modem) would be my first step, but I have suitable ferrite rings to hand. The other possibility is the RF energy is getting in via the phone wiring - changing the BT supplied flat cable between modem and filter for a twisted pair one would help, as would winding that cable through a ferrite ring as I've just described. I'd also do my best to get the phone cabling to run at right angles to the power wiring, but you can't do much about the fixed wiring in the walls.


My favourite fix of all would be to put the Homeplugs in the bin and replace them with an Ethernet cable - but, as a radio amateur, I dislike all technologies that inject RF into power wiring.

The home plugs aren't on a different rings, the router and first home plug is in my landing, and the second home plug is about 5 meters away, on the same floor - i even tried a long ethernet cable so both home plugs are in the same room, but got the same result!

the slowness is only affecting internet traffic and not internal traffic, so i don't think something plugged in somewhere is causing an issue, very strange behaviour

In reply to a post by David_W:

I'd guess at an EMC issue between the Homeplug and the BT modem - probably RF energy from the Homeplug getting into the modem via its power supply or via the BT wiring.

Edit: I've just realised that billford was talking about a different brand of Homeplug to the original poster, so this second post of mine may or may not be correct.


billford's experience with the Homeplugs being interfered with by a CFL suggests that the lack of immunity may be in the Homeplug rather than the BT modem. If this is the case, the issue arises because there's a much bigger overlap between the frequencies the Homeplug uses and your new VDSL service than your old ADSL service.

If the lack of immunity is indeed in the Homeplugs, changing the cable between the BT modem and filter for a twisted pair one may help, as may winding a ferrite ring onto the BT modem's power cable (in case RF is leaking from the modem back onto the power wiring that way) but the right answer is likely to replace the Homeplugs with something else - a cable if you can, another brand of Homeplug if you must.

Edited by deleted (Thu 17-Jan-13 21:52:59)

In reply to a post by David_W:

billford's experience with the Homeplugs being interfered with by a CFL suggests that the lack of immunity is in the Homeplug rather than the BT modem.

Yes, I should have mentioned that- the internet connection (FTTC) from the main computer (iMac) doesn't go through a homeplug, and that remains fine even when intra-LAN transfers via a homeplug are essentially unusable.

Wow, just tested your theory and your right, if i transfer a large file from the router (via usb) to my pc, the open reach modem just resets itself, verified twice as i couldn't believe it, that explains that then! what a bummer, i will have to think of another way of getting internet onto some of my ethernet only devices, i wonder if another brand of home plug would have the same problem, or using my own vdsl modem?

I will look into the ferrite rings, and the other tips you have suggested first.

edit: My home plugs are dlan devolo so are the same brand!

Many thanks for your reply!

Raj

Edited by deleted (Thu 17-Jan-13 22:10:06)

It sounds like the Homeplugs are putting so much 0-30MHz RF into the BT modem that it simply can't cope.

I believe Homeplugs are a vile technology, putting RF energy onto cabling that is neither a differential twisted pair nor co-ax. This will give you two separate problems:

• your mains wiring will radiate that RF energy (in exactly the same frequency band as that used by DSL), which can be picked up directly by other equipment or can get in via cables (including the phone cabling)
• the RF energy can get directly into an affected device via its mains power supply

The usual way to figure out which one of these two problems you have is to power the affected device from batteries, which eliminates the second problem temporarily - but that is non-trivial for the BT modem which is not designed to be battery powered. You really can't blame the BT modem - Homeplug noise is often far over that specified in EMC immunity tests.

If you are determined to debug this, I'd wind a ferrite ring (following the diagram I've previously linked to carefully) on the BT modem's power lead as close as possible to the modem. That should minimise the second problem. If you're still getting problems, put another ferrite ring on the phone lead as close as possible to the modem, ideally changing that lead for a twisted pair one.


For optimal DSL speed you want to minimise the noise on DSL frequencies. A Homeplug is about the best source of noise you can get. If possible, put the Homeplugs in your nearest e-waste collection (vile things that they are) and install a cable in their place. A competent tradesperson should be able to run 5m of cable neatly for you if you don't feel confident in doing this yourself.

I'm going to look at purchasing some ferrite rings today, i'm looking on ebay, does it matter what size they are? as there's a vast variety of rings/beads on there

edit: what do you think about this bead?
http://goo.gl/qmBeL

Edited by deleted (Fri 18-Jan-13 08:57:32)

what about good old long ethernet cables? the proper way.

I actually think homeplugs need to be banned they seem very high interference. If they affect 0-30mhz How do I not know one of my neighbours are using any and affecting my vdsl?

also would a belkin filtered extension cable work?

Even then the noise will be picked up on te phone line which cannot be mitigated.


As for vile technology - I totally agree.

I found (after a comment by someone else on the BT forum) that my Homeplugs work better when the homeplug is not plugged into to a twin socket with all my other computer things plugged off the other side of the socket.

All my other computer things in this case are connected off a surge protected extension, and include computer, printer, gigabit switch and a few other bits. The modem and router are in a different place.

I knew not to connect the powerline into a surge protected extension; but was surprised how big a difference plugging it into the twin made. The powerline wasn't that close to any of the other equipment. Keeping it in the same place, but plugging into a longish mains extension itself plugged into another socket on the same ring improved speeds quite a bit. (I know a longish mains extension isn't a good idea either, but that was what was practicable in the short term.)

Text

1 23 45 67 89 1011 1213 1415 1617 1819 2021

signal ~~~~~modem-->router----/long ethernet cable/-----> switch --> powerline1 --/different ring/----> powerline2 --> computer2                                                   |                                                  ' ---> computer1    power~~~~~      twin  ----> surge protected extension --> switch    socket                              |----> computer1               |                                 '----> etc      '-> powerline1                                             <<<<<<<< BAD         twin  ----> surge protected extension --> switch    socket                              |----> computer1                                                 '----> etc      separate --/mains extension/--> powerline1                   <<<<<<< BETTER                                              socket

Well, in the end, i realised i could keep my network doing everything i wanted to, using standard wireless and a wireless bridge, so the home plugs will go on ebay shortly, thanks for the replys guys, feels great using my infinity at the speed i was expecting!