Bests & Worsts Reviews from Amazon

I had opportunity to test two different cable modems on Comcast business service. One was Motorola SB6121 and the other Zoom 5341. Both are DOCSIS 3.0, which is required for high speed cable service. Comcast tech support was not thrilled about Zoom while they praised Motorola SurfBoard high. As it turned out, average Comcast technician, who suppose to activate the modem, has a trouble with the Zoom serial number. My configuration of Comcast service in this case is 2 times 50 Mb/s download and 10 Mb/s upload speed. This service supposes to supply over 1000 users with Internet access, load balance mode. First line was activated with Zoom modem and everything went well for several days. To the second line I attached Motorola modem; Comcast managed to deactivate Zoom modem on the first line in process, though. Initial test of Motorola showed expected values in download and upload speeds. However, with network connected to it, Motorola download speed didn't reach more than 10 Mb/s download with upload of 2 Mb/s. After 24 hours of 1000 people complaining, Comcast Technician came to check the installation and re-activate Zoom modem. Test of Motorola modem with a single laptop connected didn't show any abnormality: Download and upload speed were at nominal values. Since I couldn't put in place my load balancer yet, I switched the network to the Zoom modem and made 1000 surfers happy again. In a couple of days my load balance configuration should go live, using one Motorola and one Zoom modem. I intend to update this review with the result of Motorola performance in this configuration, for potential buyers interested in the Motorola SB6121. Well, I decided to buy Comcast Internet service for home and I didn't have dilemma which modem to chose; Zoom it is. I ordered on-site installation because my cable coax had to be replaced and expecting confusion with Zoom serial number (that happened as expected, too). Anyway, Comcast got it online and my modem is happily blinking, ever after (two weeks in service). The one ordered here has slightly different housing than the first one I dealt with (bought at Microcenter); I assume that Zoom made a change in design and this one does not get as warm (as the other one). Price difference between Zoom and Motorola on Amazon is not worth mentioning; while Motorola is a big name in communication equipment I felt more comfortable for going with Zoom this time. **** UPDATE **** After year in service at home, this modem had 100% uptime - no glitches whatsoever. I cancelled my service with Comcast few days ago; price for my service went higher than I find justified. I signed up with WOW and transferred this modem to the new service - no problems.