Internet slows down intermittently.

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
A client is reporting that his internet speed is high for several days at a time and then will intermittently slow down to about 1/4 speed. He's using a Spectrum cable modem. I think I heard him say his high speed was 260 mbps. The cable between the modem and the router is probably CAT5 and runs about 30 feet. I put a cable tester on the cable and it passes. Is there a reason this would happen?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Cable internet speed is probably more use-dependent than any other source. The greater the internet use in the neighborhood, the slower the speed. Have them keep track of the time of day the slow-downs happen and look for patterns.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I had a similar problem years ago and I had to replace my router. It could be the router but bypass the router by going directly to the modem with an ethernet cord. If you still have the problem it is the modem or the connection on utility end
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
I would be very suspect of the cable modem. Try rebooting it when this happens. Consider replacing the modem as they are all mostly junk today.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
A client is reporting that his internet speed is high for several days at a time and then will intermittently slow down to about 1/4 speed. He's using a Spectrum cable modem. I think I heard him say his high speed was 260 mbps. The cable between the modem and the router is probably CAT5 and runs about 30 feet. I put a cable tester on the cable and it passes. Is there a reason this would happen?
Crappy modem and/or crappy backbone
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Comcast was trying to upsell more speed to one of my customers, she lived by herself, had quite a few Nest thermostats, and a couple of doorbells. The doorbells were set medium resolution, the thermostats use very little data, three Roku tv’s. The internet would crash every 10-20 seconds, so they wanted her to upgrade from 25 mbs saying that would fix her problem. I told them the cable that was laying on the ground in her yard all chewed up from her neighbor running a track dump cart up and down the bank was probably the reason. After finding out their sales pitch wasn’t working, they finally said they would send someone out to check it.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
A client is reporting that his internet speed is high for several days at a time and then will intermittently slow down to about 1/4 speed.
How does he know? I haven't checked my internet speed in years. What's he doing that he would notice the drop. Lots of people would be happy with 75mbps. Besides, even if he saw 260mbps, what's the cable company saying they will provide him with? Anything in the agreement about cutting speed after he reaches a certain usage cap or because of heavy usage by other subscribers? Bandwidth is a big problem today with everybody working from home and kids remote learning.

-Hal
 

paulengr

Senior Member
How does he know? I haven't checked my internet speed in years. What's he doing that he would notice the drop. Lots of people would be happy with 75mbps. Besides, even if he saw 260mbps, what's the cable company saying they will provide him with? Anything in the agreement about cutting speed after he reaches a certain usage cap or because of heavy usage by other subscribers? Bandwidth is a big problem today with everybody working from home and kids remote learning.

-Hal
A cable company basically uses some extra cable channels to carry data. You get “up to X speed” but never a minimum Y speed for a reason. Everyone in your neighborhood is sharing the SAME “up to X speed”. So the more the neighbors run say YouTube videos the more it sucks.

Contrary to popular belief fiber is the SAME. You are sharing ONE fiber with video for the whole neighborhood. Gigabit only happens if nobody else is using it.

DSL is different. Each phone line is truly independent. It has a top speed lower than cable but it’s all yours.

Except...we get into over subscribing service. So the main internet backbones across the country (long distance carriers) have effectively nearly unlimited bandwidth. The limitation is the bandwidth of your ISPs connection to the long distance carrier. Frequently they have far less bandwidth than what they should have based on subscribers.

This is over and above crappy lines connecting your house. Cable companies for instance often skimp and don’t use RG-6 so the cable rots in 5-10 years. Similar issue with phone. Modems are an issue too. I’ve only seen one last over 3 years. Cheap routers too.

You can use “trace route” to look at ping times. It is usually obvious where the bottleneck is.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I've had to have cables outside repaired several times because squirrels chewed through them. The last time this happened the technician that replaced the cable said he had replaced it with cable that had an insulation that tasted bad to squirrels. It May have worked because I haven't had the problem since.
 
Contrary to popular belief fiber is the SAME. You are sharing ONE fiber with video for the whole neighborhood. Gigabit only happens if nobody else is using it.

DSL is different. Each phone line is truly independent. It has a top speed lower than cable but it’s all yours.
Well... either fiber or DSL will be your own line from your house to the node (not so for cable modems). Once at the node, all the traffic falls into a switch/concentrator of some kind and runs on shared fiber from there, but that's how the Internet works- much intermingled traffic on a single path.

Except...we get into over subscribing service. So the main internet backbones across the country (long distance carriers) have effectively nearly unlimited bandwidth. The limitation is the bandwidth of your ISPs connection to the long distance carrier. Frequently they have far less bandwidth than what they should have based on subscribers.
That is a big problem, everyone "oversubscribes" to some extent (how many people with a 200MB/s home connection actually fill the pipe? very few; they're buying speed/latency, not capacity), but the better ISPs are more careful about it. And some of the big ones, like comca$t will run their own long-distance fiber or contract for dark fiber if it's cost-effective to do so.

Then there's private peering arrangements vs internet exchange points and their link saturation, which really gets off into the weeds of network operations. Don't go there, it's not safe.....
 

paulengr

Senior Member
Well... either fiber or DSL will be your own line from your house to the node (not so for cable modems). Once at the node, all the traffic falls into a switch/concentrator of some kind and runs on shared fiber from there, but that's how the Internet works- much intermingled traffic on a single path.



That is a big problem, everyone "oversubscribes" to some extent (how many people with a 200MB/s home connection actually fill the pipe? very few; they're buying speed/latency, not capacity), but the better ISPs are more careful about it. And some of the big ones, like comca$t will run their own long-distance fiber or contract for dark fiber if it's cost-effective to do so.

Then there's private peering arrangements vs internet exchange points and their link saturation, which really gets off into the weeds of network operations. Don't go there, it's not safe.....
Dark fiber is basically free. You just pay federal “rent control” to mount your equipment in rack space. Knowing where the dark fiber is allows local telecom companies access to high bandwidths like OC-48 almost for free.

Private peering and public exchanges are basically where large regional carriers connect. It largely has little to do with perceived bandwidth especially because CDNs carry most of the traffic.

I don’t know about today but back when Netflix was two companies (DVD rental and streaming) there were a total of 3 IT techs. One for each “side” and one that was sort of shared. One of the two primary techs was a friend and quite after a couple years of 72+ hour weeks. He said the pay was fantastic but he couldn’t spend it because he was always at work. Netflix streaming was largely on AWS and Akamai. Netflix itself was small.
 

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
The client noticed the reduction in speed because when streaming on his TV, the show started stuttering. He ran speed tests on his various computers and found the speed was 1/4 as fast as when it was fast. There are also two other users playing video games in the household. I know from personal experience that video games can suck up a lot of bandwidth.

Nobody has said anything about the CAT5 cable between the modem and router. So can I assume it is fast enough to not be part of the problem?

If he wanted to check if the speed reduction was due to problems outside the house wiring, could he plug a computer directly into the modem (bypassing the router) and do a speed test?
 

egnlsn

Senior Member
Location
Herriman, UT
Occupation
A/V/Security Technician
Is it the internet that's slow or is it the WiFi? Most consumers think they're the same thing. If either one is slow, they'll say the internet is slow. Could simply be a matter of changing the channel on the WiFi router.
 

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
Is it the internet that's slow or is it the WiFi? Most consumers think they're the same thing. If either one is slow, they'll say the internet is slow. Could simply be a matter of changing the channel on the WiFi router.
No, we are definitely talking about the network wiring here. I was called because I had installed CAT6 to several rooms. After some troubleshooting, we narrowed the problem down to the modem to router jumper which was existing except that put a new connector on one end. A cable tester showed a "pass" condition. All the new cables I installed passed also, but I double-checked the punchdowns just in case. So it's either the modem/router cable, or something outside.
 

egnlsn

Senior Member
Location
Herriman, UT
Occupation
A/V/Security Technician
So, utilizing a laptop, run a speed test <speedtest.net> from one of the outlets, again at the uplink to the router, and another one at the cable modem. You should be reasonably close at all 3 points.

Is the router setup with a VPN? I've not seen a VPN yet that doesn't slow things down.
 

egnlsn

Senior Member
Location
Herriman, UT
Occupation
A/V/Security Technician
A cable company basically uses some extra cable channels to carry data. You get “up to X speed” but never a minimum Y speed for a reason. Everyone in your neighborhood is sharing the SAME “up to X speed”. So the more the neighbors run say YouTube videos the more it sucks.

Contrary to popular belief fiber is the SAME. You are sharing ONE fiber with video for the whole neighborhood. Gigabit only happens if nobody else is using it.

DSL is different. Each phone line is truly independent. It has a top speed lower than cable but it’s all yours.

Except...we get into over subscribing service. So the main internet backbones across the country (long distance carriers) have effectively nearly unlimited bandwidth. The limitation is the bandwidth of your ISPs connection to the long distance carrier. Frequently they have far less bandwidth than what they should have based on subscribers.

This is over and above crappy lines connecting your house. Cable companies for instance often skimp and don’t use RG-6 so the cable rots in 5-10 years. Similar issue with phone. Modems are an issue too. I’ve only seen one last over 3 years. Cheap routers too.

You can use “trace route” to look at ping times. It is usually obvious where the bottleneck is.
I've had cable modems since the service first became available in my area, which was mid-90s, and the only time I've been much below the "up to" speeds, was when the service was new and AT&T Broadband was the service provider. At that time, speeds were all over the place. Since then, the industry has matured and speeds are much more regulated. Over the past 15 years or so, I have seldom been much below my advertised speeds. Usually it's been a little more than what I've been paying for. When I checked it 9:00 this morning, I was running at 926down and 43 up. At 7:55 this evening, 913 down and 43 up. That's coax from the node to my cable modem.

I don't understand the "don’t use RG-6 so the cable rots in 5-10 years" comment. The cable type has no bearing on how long it lives in the ground. The construction is the same regardless of whether it's Series 59, 6, 7, or 11.

Yes, DSL is different, but it is also distance-limited. You have to be within 18,000 feet of the DSLAM to be able to get the service. The further out you are, the slower your speeds.
 
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