I have an 1841 router that I use as a firewall and gateway for a small LAN of about 12 PCs. The 1841 is connected with a 100MB full duplex Ethernet connection to a Samsung ISP router which has two bonded T1 for a 3MB channel to the Internet.
Testing connection speeds with various test sites I noticed that download speeds were quite close to the theoretical maximum of 3MB. I get consistent results between 2.6 and 2.8MB down. However upload speeds are quite different. The max I have seen is 2.2MB and it usually averages somewhere
between .8 and 1.2MB down. I inquired with the ISP and they had me connect a laptop directly to their router with a public IP. Speed test from there showed a very consistent 2.8MB up and down.
At this point they of course claim the problem is on my end and close the case and I can't blame them because it does seem exonerate them.
The 1841 does nothing else on this LAN. No IPSec, no IDS or VoIP services nothing but Internet gateway. As such the only services running on it are IP routing with CEF enabled and inspect/CBAC services. Interfaces do not show any CRC or other errors.
I tried to turn off the inspect/CBAC which is the only thing left to turn off but when I do web browsing doesn't work.
What can be causing this? How can I troubleshoot?