Can no longer copy large files 2GB and greater to Dropbox, Backblaze, or AWS after planned downtime to enhance the Xfinity network 9/13

You might have better luck with rsync over ssh with these options.  You'll still have to restart it if the connection closes with a broken pipe:

--inplace               update destination files in-place
--partial               keep partially transferred files
--append                append data onto shorter files
--progress              show progress during transfer

Take a look here for connection problems, especially the "Check your signal levels" section:  https://forums.xfinity.com/conversations/your-home-network/internet-troubleshooting-tips/602dae4ac5375f08cde52ea0

Perhaps your connection isn't very stable in the first place now.

Most definitely, the uncorrectable errors aren't good.  That's not helping.  I also don't like the skew on the downstream power.  Should be pretty close on every channel.  Upsteam?  Meh.  Well, you can't see upstream receive power on that one (most of them).    

I guess you're looking for splitters, kinks in cable.  Perhaps cable end oxidation.  Anything that causes a reflection.  Take them apart, scuff up the center connector.  It's not terribly awful, but it's not right. 

If you get stuck, you need a tech visit.  If there aren't any splitters, and it's not on your end in the house, that's free.  If it IS in your house, or they find splitters, it is not. 

@user_rn0945 

Your post with that pic of the error log entries was marked as being "Private" by the forum software because it contains CM MAC and the CMTS MAC addresses. They are considered to be personal information. The posting of personally identifiable information is a violation of their forum guidelines. Please delete that pic only.

What you can do instead is to copy and paste all of the text (instead of using an image) but you'll need to redact all of the CM MAC and CMTS MAC addresses. The forum bot will not allow your post to be seen publically.

@flatlander3 wrote:

"Well, you can't see upstream receive power on that one (most of them)."

FWIW. Actually, it's all of them. That value can only be read by Comcast employees by them polling the CMTS.

I'm having this exact same problem since the "upgrade". Large files mysteriously fail partway through the upload. I can't use rsync because this is an AWS Docker image repository, not a server. Given we just had XFinity out recently to completely replace the cable from the pole to the house, and I *didn't* have these issues before the change, this is almost certainly an issue with the upgrade and not any sort of equipment in or around the house.

To anyone who also sees this post (and rnaegele): hit up Xfinity with a chat support request and ask them to send your cable modem a new bootfile. I just did that and it seems to have resolved the problem with uploads. I'll post again in a few days once I'm sure it's a solid fix but so far it looks promising.

****UPDATE**** Tried the bootfile with tech support and that did not help my scenario. Still running into unstable uploads. All downloads seem good. After eliminating a splitter in my line and upgrading to an RG6 type coaxial cable my download numbers I believe have improved, however, it appears to me that the upload numbers of around 33-35 dBmV is lower than what Arris recommends for the SB8200 here: https://arris.secure.force.com/consumers/articles/General_FAQs/SB8200-Cable-Signal-Levels/?l=en_US&fs=RelatedArticle. Seems like they want it to be between 45-51 dBmV for it to be in spec. What does anyone recommend? Should I schedule a tech to come out?

Here's my new numbers: