LAN connection speed issue

[tjbeaumont]

Hi all

Having a very strange problem. I recently had 900Mb FTTP installed and the BT connection is rock solid. However my internal LAN is doing strange things, the main issue being the download speed on my LAN devices frequently drops to 10Mb (up and down, tested at speedtest.net).

A simple reboot of my Netgear switch solves the problem and I'm back to 900Mb again. This is happening across a range of LAN devices, all connected via ethernet. I've even replaced the switch but it keeps happening. 

Appreciate this is not really a BT issue but curious if anyone has any ideas. I'm starting to wonder if there might be an issue with Netgear switches being unable to cope with a 900Mb FTTP connection 🙂 

[Keith_Beddoe]

@tjbeaumont 

The Netgear switch is failing to auto-negotiate the correct link speed. This can be due to a long or incorrect type of Ethernet cable between the home hub and the switch. Link pulse timing issues due to poorly matched hardware, can also cause issues.

See https://en.wikipedia.org/wiki/Duplex_mismatch

If what I have suggested does not cure the problem, then a managed Ethernet switch like the Netgear GS105E or GS108E, both allow you to lock the link speed on specific ports using an easy web based interface.

[tjbeaumont]

@Keith_Beddoe 

Yes good point, thanks - the ethernet cable between hub and switch is very long. Not much I can do about that, so will look into a better (managed) switch.

[Keith_Beddoe]

Make sure the long Ethernet cable is a good quality fully wired one. You may even have to interpose an additional switch if its over 90 metres.

A managed switch may still have issues if there is a lot of signal degradation.

[TimCurtis]

@tjbeaumont 

Personally I'm not a fan of Netgear switches and they don't necessarily cope with BT's multicast transmission very well if you have BT TV Subscription channels.

I'd go for TP-Link equivalents like the TL-SG105/8 or their managed equivalents 105/8E.

[tjbeaumont]

@Keith_Beddoe  @TimCurtis  - thanks both for your comments. The length is certainly less than 90m and well insulated, I'm going to try out the TP-Link as I've read a few other articles about Netgear. Will let you know how is plays out.

[countrypaul]

You should make sure the Ethernet cable is well away from any mains cable and other things that can cause interference - somthing that is more noticable at higher ethernet speeds.  If the Ethernet cable runs parallel to a mains power cable for any distance you will very likely have problems.

[tjbeaumont]

@Keith_Beddoe  - quick update on this issue as it gets a bit weirder...

So I got a tp-link SG105E and forced the port to 1000MF which appeared to stabilise the connection, but not completely. I also re-terminated both ends of the cable and confirmed all was fine with a cable tester.

Intermittently though, the port is still disconnecting and I've confirmed whenever this happens, pin3 is failing on the cable tester. And then sporadically it starts working again (it often starts working after I've used the cable tester but I think that has to be a coincidence).

I can only conclude there's a break on the cable somewhere, although replacing the cable would be a big job.

Any other thoughts??