Slow FiOS throughput -- potential fixes

With FiOS (high speed fiber optic) connections becoming ever more available geographically speaking, a number of Mac users are taking the plunge into the relatively expensive service that promises download speeds of up to 30 Mbits per second, and upload speeds of 5 Mbits per second.

Unfortunately, some users are finding that their Macs deliver relatively dismal throughput when compared to PC counterparts. In at least some cases, the problem only manifests on systems connected via their AirPort cards.

MacFixIt reader Larry writes: "Just had a FiOS installed and am running 10.4.8. Supposed to get 30/5 for $179 per month. Only get 10/3 after trying about everything imaginable including two different computers hard wired to router/modem. The installer tech tried his own PC  computer and got 30 ."

We reported on this issue last year, but the small installed base of FiOS users at the time precluded any general conclusions other than the fact that Apple's Broadband Tuner sometimes had the intended effect of increasing throughput.

In cases where AirPort is involved, there may be no real solution other than attempting to eliminate interference from other 2.4 GHz devices (phones, other wireless routers), switching channels, and other workarounds listed in our AirPort tutorial. A 30 Mbps downstream connection will push the real-world limits of an AirPort Extreme Base station -- rated at 54 Mbps but more likely to deliver 20-40 Mbps. Try bypassing AirPort (plugging the Ethernet cable directly into your Mac) and see if speeds improve to determine if wireless connectivity is the bottleneck.

In cases where AirPort is not involved, the aforementioned Broadband Tuner is a good first measure. Other potential fixes including switching router brands/models, and manipulating MTU settings with a utility like IPNetRouter. Experiment with values in the 1500-range. Many users have found success with a setting of 1492, others with 1456.

Feedback? Late-breakers@macfixit.com.

Resources