Well Express doesn't generally fail. If you've tried on different computers it is likely an issue with your 2598. Can you check how much spare space you have in your device? Also which map are you trying to update?
Are you trying to update over wi-fi or is the PC cabled directly to your router? If over wi-fi try cabling direct to rule out a wi-fi issue.
What I finally did was to use the 5.4 version, as it seems to remember where the download failed. The newer versions looked like they were starting over every time. Then I just ran the update over and over and over and it FINALLY all downloaded. Since I don't have issues with any other software when downloading, I fault something with Garmin's Express, or their servers. So it's now updated, and I'll just hammer the update over and over on the next map update. Stupid, but there it is.
Glad you resolved it. Sounds like your ISP is throttling your download, as I posted normally the Express download is smooth and trouble free, my devices generally take around 30 minutes. Those that do have problems find it's invariably down to issues somewhere in their system, anywhere from the device up to their ISP, but nothing to do with Express which these days is extremely stable, at least for automotive devices.
