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Attenuator stopping connection?

kashi394
I've been here awhile

I recently moved and a Rogers tech setup my wifi but installed a 9db attenuator which i didn't really care about but i had to unplug the cable connection so i could paint my wall and when i went to hooked it backup i got no internet but the wifi signals were there and when i took it off and directly connected the cable to my modem there were no issues. Is there a reason for this?

 

 

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Re: Attenuator stopping connection?

@kashi394 all of your downstream signal levels are high, typically they should be down at 0 dBmV.  The signal to noise ratios are at the bottom of the range of where they normally are, 36 to 40 dB.  The upstream levels are also low, typically they are in a 36 to 40 dBmV range.  

 

Adding the attenuator would drop the downstream levels down to approx -3 dBmV and push the upstream up to 39/40 dBmV.  

 

The modem can probably do fine with the downstream numbers, the upstream is probably an issue.  That might result in retransmit requests from the Cable Modem Termination System which the modem connects to.  You might see a reduced data rate due to those signal levels.  Adding an attenuator to bring those levels up is a false economy, personal opinion as the outgoing signal level drops as it transits thru the attenuator if in fact that particular attenuator affects both downstream and upstream levels to the same signal drops.  

 

Are you in an apartment/condo/townhouse type of building.  Its typical to see high downstream levels in those buildings.  If you are in one of those building types, then perhaps the low upstream level won't be a problem.  You could call tech support and ask the CSR to run a signal check on the modem and ask if the upstream signal level and signal to noise ratio at the CMTS are within acceptable levels.  While you can see the downstream levels, the CMTS doesn't report its received numbers back to the modem, so, a call to tech support is required to determine those levels at the CMTS. 

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Re: Attenuator stopping connection?

Datalink
Resident Expert
Resident Expert

Sounds like the center pin on one end of the attenuator may have been bent, preventing that pin from reconnecting.  Without an internet connection, the modem wifi would be up and running, but, you wouldn't have internet access.  Same for any other modem or router, wifi will run but it won't care about whats at the other end of the modem or router.  

 

The tech most likely installed the attenuator for a good reason.  Without it, the cable signal levels are probably too high, which might cause problems.  Can you log into the modem, navigate to the STATUS .... DOCSIS WAN tab, copy the downstream and upstream table and paste that into a post.  The copy and paste process will paste in the text contents of the table.

Re: Attenuator stopping connection?

kashi394
I've been here awhile
Downstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDSignal noise ratio (dB)
1615000000256QAM6.1001135.595
2579000000256QAM6.000535.595
3585000000256QAM5.900635.595
4591000000256QAM5.900735.595
5597000000256QAM5.200835.084
6603000000256QAM5.500935.595
7609000000256QAM6.0001035.084
8303000000256QAM5.000136.610
9621000000256QAM6.2001235.595
10633000000256QAM6.6001335.595
11639000000256QAM7.0001435.084
12645000000256QAM6.6001535.084
13651000000256QAM6.8001634.926
14657000000256QAM6.9001734.926
15663000000256QAM7.2001835.084
16669000000256QAM7.1001935.084
17675000000256QAM7.6002035.084
18681000000256QAM7.3002135.084
19687000000256QAM7.4002235.595
20693000000256QAM7.2002335.084
21699000000256QAM6.9002435.084
22705000000256QAM6.9002535.084
23711000000256QAM6.4002634.484
24717000000256QAM6.3002734.346
Upstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDBandwidth
138596000ATDMA - 64QAM31.50033200000
230596000ATDMA - 64QAM30.50016400000
323700000ATDMA - 64QAM29.75026400000

Re: Attenuator stopping connection?

@kashi394 all of your downstream signal levels are high, typically they should be down at 0 dBmV.  The signal to noise ratios are at the bottom of the range of where they normally are, 36 to 40 dB.  The upstream levels are also low, typically they are in a 36 to 40 dBmV range.  

 

Adding the attenuator would drop the downstream levels down to approx -3 dBmV and push the upstream up to 39/40 dBmV.  

 

The modem can probably do fine with the downstream numbers, the upstream is probably an issue.  That might result in retransmit requests from the Cable Modem Termination System which the modem connects to.  You might see a reduced data rate due to those signal levels.  Adding an attenuator to bring those levels up is a false economy, personal opinion as the outgoing signal level drops as it transits thru the attenuator if in fact that particular attenuator affects both downstream and upstream levels to the same signal drops.  

 

Are you in an apartment/condo/townhouse type of building.  Its typical to see high downstream levels in those buildings.  If you are in one of those building types, then perhaps the low upstream level won't be a problem.  You could call tech support and ask the CSR to run a signal check on the modem and ask if the upstream signal level and signal to noise ratio at the CMTS are within acceptable levels.  While you can see the downstream levels, the CMTS doesn't report its received numbers back to the modem, so, a call to tech support is required to determine those levels at the CMTS. 

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