TP-Link TD-W8951ND ADSL router WiFi speed drops

[starLED]

I have TP-Link TD-W8951ND ADSL router for a couple of years working fine with my PC connected to Wifi.
Now Internet speed on my PC drops frequently to 0 mpbs over Wifi and after couple of minutes returns back.
When I connect PC with LAN cable directly to the router, internet speed is constant.
I have tried different router to exclude PC issue, and it's working fine.

What can be a hardware problem?
I've looked at the PCB but I don't see anything obvious.
Maybe overheating is the issue?
Maybe wire for antenna?

 

[Pommie]

Could be channel availability. If you have an Android phone install Network Analyser and check how much traffic there is. I live in an apartment block with lots of networks competing for channels. I only got good WiFi once I switched to a 5 GHz network (not 5G).

Mike.

 

[rjenkinsgb]

As Pommie says.
2.4GHz is unusable in many places due to the amount of overlapping systems.

Note that the channel numbers are pretty irrelevant as they are a leftover from early systems.
11g WiFi used four numeric channels as a block and you could just have three systems coexisting in countries with 11 channels, using 1, 6 & 11. (Or four using 1, 5, 9 & 13 in 13 channel countries).

A lot of newer 11n systems use EIGHT channels as a block, 2/3 of the entire band - so it's literally impossible for any two to coexist in range of each other without slowdown and blocking effects.

Then add in non-WiFi 2.4GHz, everything from video senders, microwaves, baby alarms and (in some countries) DECT cordless phones... None of those are visible on WiFi based channel analysers, as the signal format is not recognised by WiFi receivers - but the signals still interfere with or block the WiFi signals.


The basic rule is never use WiFi for any fixed device like a desktop PC or TV etc.
Use wired Ethernet of fast Homeplug, that does not travel outside the house or get interference from other houses..
If you have to use WiFi, use 5GHz where there is vastly more space for systems to coexist without problems.

>end rant< (Retailers pushing WiFi for fixed devices is one of my pet hates, if you've not guessed that!)

I have experienced failures in two or three TP-Link routers supplied to customers - but it's always been the DSL side, not the LAN side; they still work fine when reconfigured as APs, so I don't know how likely a WiFi hardware fault is.
The fact that your system recovers without being shut down to cool seems to make it unlikely

 

[starLED]

I have tested different channels and used Network Analyzer to choose the proper one.
Even if I place phone near to the router, the Wifi speed drops, and not only that but Wifi connection is lost all together briefly. Also same happens to the PC.
I suspect more it's a hardware issue.
I used a lot of TP-Link routers in the past, and they all have the same issue after a couple of years.
What exactly can it be?

 

[Inquisitive]

Try a different brand of router and see if the problem persists.

 

[Nigel Goodwin]

I have tested different channels and used Network Analyzer to choose the proper one.
Even if I place phone near to the router, the Wifi speed drops, and not only that but Wifi connection is lost all together briefly. Also same happens to the PC.
I suspect more it's a hardware issue.
I used a lot of TP-Link routers in the past, and they all have the same issue after a couple of years.
What exactly can it be?

Most likely high ESR electrolytics in the external PSU, a VERY, VERY common problem on routers (and much other equipment) - I've even seen it where it's wiped out ADSL for most of a street.

If you've got a laboratory power supply, try feeding it from that instead and see if it works OK.

It would have been a good idea to try the PSU from one of the new ones on a 'faulty' old router, and see if that worked - but that ship has long since sailed.

 

[starLED]

I used another PSU and it seems it's working fine now.

 

[Nigel Goodwin]

I used another PSU and it seems it's working fine now.

Take the old supply apart, and you'll 'probably' be able to see a swollen or leaky electrolytic.

I've found the best way to split them is to saw round the seam with a junior hacksaw, gives you better control than a sharp knife or Dremel - oops, straight through the transformer

 

[starLED]

I have a Villager phone repair set that includes minipry bar.

 

[starLED]

I thought adapter can be pryed out, but it seems that is welded together, so I will need a hacksaw after all.
Question is, how to put it back together?

 

[Nigel Goodwin]

I thought adapter can be pryed out, but it seems that is welded together, so I will need a hacksaw after all.

I knew that!

That's why I specified a saw.

Question is, how to put it back together?
View attachment 137352

Run a bead of epoxy resin round the seam, and wrap insulation tape across the two halves to clamp it together. You can use other glue if you wish, but epoxy is probably more permanent, and fills the gap from the saw cut.

 

[rjenkinsgb]

I find that a lot of cases such as that & laptop power supplies etc can be split by repeatedly and solidly tapping around the seam with something like a screwdriver handle, to flex and fatigue it until something gives - often the adhesive.

Once it splits enough, a metal table knife is a good prying tool to elongate the splitting, as they have rounded surfaces that don't mark things too much but are also very rigid.

 

[starLED]

I find that a lot of cases such as that & laptop power supplies etc can be split by repeatedly and solidly tapping around the seam with something like a screwdriver handle, to flex and fatigue it until something gives - often the adhesive.

Once it splits enough, a metal table knife is a good prying tool to elongate the splitting, as they have rounded surfaces that don't mark things too much but are also very rigid.

I tried that, you can see it on the image, there's a hole made by screwdriver.
I tried to pry it out, but the damn thing wont move a notch, it's like a one solid peace.
There's no other way except to cut it.

 

[Nigel Goodwin]

I find that a lot of cases such as that & laptop power supplies etc can be split by repeatedly and solidly tapping around the seam with something like a screwdriver handle, to flex and fatigue it until something gives - often the adhesive.

Once it splits enough, a metal table knife is a good prying tool to elongate the splitting, as they have rounded surfaces that don't mark things too much but are also very rigid.

It's normally either thermally welded, or solvent glued - and doesn't like coming apart - which is why I (eventually) settled on the hacksaw method, which causes minimal damage, and allows you to glue it back together easily.

 

[rjenkinsgb]

All it requires is the correct level of controlled "percussive therapy"..
Its extremely rare I've failed with this technique.

I did one of those Euro plug style PSUs a few days ago to get the HF transformer, but have already thrown the case away. I've found a redundant one of similar size but UK style plug as a demo.

It took around 3 - 4 minutes solid tapping around the seam for it to separate. The only bit that would not go was the cable entry end, I had to lift the top end and put the metal spudger as low down as I could as a fulcrum, then squeeze the top back to pop open the base. You can see a slight dent in the parts near the top of the first photo, where the tool was positioned.

Just to confirm, this was extremely well attached before I attacked it - no sign of flexing anywhere when I tried squeezing and twisting the case.

 

[starLED]

I'll give it a try.