Visitor
•
9 Messages
XB8 Modem not reaching max upload speeds
Hello,
I've been having this issue since December 2025. I have an XB8 modem with a 2gig plan, and I'm supposed to be getting up to 250mbps upload speed. When I got the modem in December 2025, it was reaching those upload speeds for a few days before plummeting to around 7mbps for several months. If I removed a connector or barrel on the line, it would go back to around 250mbps for a day or so before dropping back down to around 7mbps. It seems like once a month it reaches full potential then drops dramatically afterward. Lately, the upload speed has been steady between 30mbps-50mbps.
I've tested my house line, the meter checks fine. All connections are tight and secured. I plugged the XB8 modem directly into my drop point outside the house and tested speeds, and the upload was still severely low. That leads me to believe there's either a problem with the drop to my house or my XB8 needs to be reprovisioned. It is my understanding that there should be an OFDMA channel in my upstream table at all times; however, it's only there on the rare occasion my speeds are reaching the max.
This is my upstream table as of today 9/21/26:
|
Upstream
|
Channel Bonding Value | ||||
| Channel ID |
17
|
18
|
19
|
20
|
|
|---|---|---|---|---|---|
| Lock Status |
Locked
|
Locked
|
Locked
|
Locked
|
|
| Frequency |
16 MHz
|
22 MHz
|
29 MHz
|
35 MHz
|
|
| Symbol Rate |
5120
|
5120
|
5120
|
5120
|
|
| Power Level |
59.0 dBmV
|
59.0 dBmV
|
59.0 dBmV
|
59.0 dBmV
|
|
| Modulation |
QAM
|
QAM
|
QAM
|
QAM
|
|
| Channel Type |
ATDMA
|
ATDMA
|
ATDMA
|
ATDMA
|
|
Regardless of what the issue is, I would greatly appreciate the support in figuring this out so I can run a business online without having to worry about speeds or upload problems.
Thanks,
Andrew
Community Best Answer
user_ctj0i7
Visitor
•
9 Messages
8 days ago
Update: 9/25/26
Technician came out today and checked my drop connection and all the junctions on the street in our court. He replaced the drop connection and added a ground wire, and at one of the junctions across the street, he found water damage that affected a cable/connection in that box. He was able to replace the damaged cable/connection, and all tests showed excellent power levels now on the upstream--I've never seen power levels this good before on upstream.
The technician did advise me to allow a full 24hrs before the modem fully adjusts to the new signals and for it to stay locked on to them. I will continue to monitor my upload speeds over the next weeks since in the past, this issue would come and go. I'm hoping his repairs were able to finally solve the issue. Right now, upload speeds are amazing.
- Andrew
(edited)
4
EG
Expert
•
121.8K Messages
12 days ago
The upstream power is way out of spec !!! If it's like that at the outside demarc point, you'll need a tech out to investigate.
1
0
EG
Expert
•
121.8K Messages
12 days ago
Yep. Good luck with the tech visit ! Please post back with how it goes.
6
0
EG
Expert
•
121.8K Messages
8 days ago
@user_ctj0i7
Thanks for the update. Looks good ! Hope that does it !!
0
user_ctj0i7
Visitor
•
9 Messages
2 days ago
As I suspected, it's been almost a week since the technician visit, and the problem has already returned.
This is the norm, unfortunately. Something will "get fixed" or the modem will be unplugged for a few hours, and then the upload speed will be fine for about a week, then the modem fails to lock onto the OFDMA channel again, and my uploads cap at 30-40mbps.
I don't know what else to do. The technician said he had fixed damage he found and replaced a few things at my drop. Not sure why it's still having this issue. It's only the upload speed that is affected.
(edited)
3
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user_ctj0i7
Visitor
•
9 Messages
15 hours ago
UPDATE: 10/2/26
The same technician came out this afternoon and ran some diagnostics on the line again from the drop point. He confirmed connection to the modem was good, but he was still seeing an issue from the drop to the street, so the issue is indeed outside the house. He rechecked the junctions on my street, and replaced another connection in one for now. He also put in a ticket last visit for a new line through the junction boxes to my house, and today he followed up on that ticket to make sure it was confirmed. In about 7-10 days, he said, a crew will be out to replace the entire run from the junction boxes to my drop point.
Since he said everything looked good above ground, the technician and I both believe there's damage to a cable underground, so we're hoping a brand new line resolves the issue. He told me the new line will be a single cable run (whereas the one now is multiple cables connected together) and it's thicker and more sturdy than the old lines. My neighborhood is almost 30yrs old, so I imagine at some point part of the cable might have been disturbed somehow.
I will report back after the construction crew arrives and completes the work.
(edited)
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