Why can't I get a stable connection to servers while downloading (using ethernet or wifi)?

Dear Mac User,

I've run into a strange network issue, which is something I've never experienced during my 30 years as a Mac user.

I noticed the issue shortly after the reinstallation of one my MacBook Pros. I experienced a system crash due to a Apple security update for 10.13.6. (What happened there, Apple?) Due to the collection of software packages on this particular Mac I reinstalled Mac OS 10.13.6 (High Sierra). I can confirm that every software program used on this Mac worked perfectly before the reinstallation. During the reinstallation no new or additional software was added.

Most software packages I already had downloaded and saved for the Mac OS 10.13.6 version. But not Adobe's Creative Cloud (and Photoshop). These software packages I had to reinstall via the Adobe server.

That turned out to be troublesome. I ended every attempt to download Photoshop with the dreaded 113 error code: Error code 113 indicates that the device is not able to connect to Adobe servers, or that the firewall settings on the device are interfering with the installation process.

The problem is that I don't have a firewall or an anti-virus software enabled.

Then the troubleshooting started:

I checked with my network provider for any possible issues that might cause download problems, but

they couldn't find anything wrong with my internet connection. I’ve also tested downloading though my

cell phone connection (hot spot, different provider). Same issues.

I’ve tested the download using a physical cable connected to the router. I’ve even tested connecting directly to the antenna, bypassing the router (and wifi) all together. Generally my internet connection works just fine. It's just during the downloading of large files I seem to have issues.

I have checked proxies and I've tried to install Photoshop via root access. The Adobe tech specialist helped me test the latter via a remote access of the machine. No luck.

I’ve now tested installing Creative Cloud and Photoshop on one of my audio production computers,

a MacBook Pro 2018 with Mac OS 10.14.6 to check if it's the actual hardware is at fault. The result is the same. Error code 113. I can't connect to the Adobe servers. I'm able to download some of the file (10-35%) before the connection crashes.

I've tried restarting, zapping the PRAMS, checked cables, adjusting DNS, deleted the network, well, I've tried every possible tip and info I've come across online so far, but without any luck.

And now I've discovered that the issue isn't related to Adobe only. My (rather large) updates for Microsoft Office 16 behaves exactly the same. Here I get a different behavior and respons from the system, but it's probably due to the same issue. Some of the file is downloaded, after a certain point the download halts and I have to break off the download (eventually).

When I think back a few days I experienced a network issue on my main production rig also (Mac Pro 6.1 running Mojave OS). Large files (plugins from a US server) just halts after a while. Smaller file sizes seem to work just fine.

What do you think causes these issues? Where can I continue to troubleshoot?

I appreciate any tips on where I can search for solutions. This issue is driving me nuts. I can't seem to isolate a particualar cause for the issues I'm having. I can't see that the network as a whole has changed much the last few years, but now it's causing me real problems:

The same issue occurs on two different Mac OS's, three different Macs and two alternative networks. Besides the download issues everything else using the internet connection seems to work just fine.

Thank you for your help!

Best wishes,

Terje