We currently have a 100MB down/100MB up network connection provided by our Internet Service provider. The most we were able to get with this router was 20Mbps down. I believe the issue could be caused by the limited MTU on the E2000 router which cannot go any higher than 1500 MTUs. Could the cause of the slow internet connection be the router and what could replace the router?
SnapOverflow
Remember that just because your ISP (claims) it gives you 100 up and 100 down, your real-world yield will be dependent on the slowest link between you and whatever you are talking to.
I would do a couple of things.
First I would run something like speedtest.net against a variety of servers. Then I would connect a laptop directly to the ISP link, configured the same way that the router is, and run the tests again. If it is faster without the router, then the router is the problem. If possible I would repeat the test with a couple of different firewalls if you have access to them.
MTU is probably not the issue here unless your ISP is doing some kind of packet handling that reduces the realizable size of the packet. If you drop your MTU to something like 1492 and things get better, then there is probably some kind of extra-ethernet protocol running -- for I believe that classic PPPoE is a trailer on the end of a packet that can cause the total packet length to exceed the MTU, meaning that the packet will get fragmented and have to be re-assembled somewhere.