Second router in DMZ of first router is running slowly since change of ISP

Paul___G

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Jul 7, 2014
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We have a home network setup as described in a few places online due to the need to have a "semi-public" (passworded wifi) network for guests etc to use and a "private" network for our own use not visible from the semi-public network.

Our main router is a DLink G604T which connects to our incoming ADSL, has a LAN IP address of 10.0.0.1 and dishes out DHCP IP addresses in the range 10.0.0.6-10.0.0.249. The DMZ port points to 10.0.0.250

Sitting at 10.0.0.250 (static IP address) is a Linksys WRT54GL router which dishes out DHCP IP addresses in the range 192.168.1.2-192.168.1.100. The router's address on the private LAN is 192.168.1.1

Everything was working perfectly when O2 were our ISP, we were getting speeds of about 2.5Mbps on the DLink router (we live in a rural village!) and 2Mbps on the Linksys.

Earlier this year, O2 were bought out by Sky and we were forced to change ISPs. The only settings I changed were the DSL settings on the DLink router and the DNS settings on both routers. However, since the change of ISP we are now getting speeds of about 3Mbps on the DLink but unusable speeds on the Linksys (e.g. 0.16Mbps!)

I cannot think what I have done wrong! I have tried swapping out the Linksys for a brand new replacement, but the same problem. I could swap out the DLink as well, but before I spend more money I am sure I must have a setting wrong somewhere rather than a hardware fault! Can anyone offer any advice? If you need more details of the precise network setup or if it's not clear from the above, please let me know.

Thanks in advance!
Paul.