Hello all, for about nine years I've happily and entirely successfully used port redirection on firstly a 2600g and latterly on a 2800g to enable external users to telnet, using a non-standard port on the WAN side, into a special-purpose PC on my LAN (the PC's IP address is 192.168.1.5, assigned by the router using DHCP with strict MAC binding enabled).
I've recently bought a 2710n and configured its port redirection (and other) settings to be exactly the same as those that have been used for years on the soon-to-be-retired 2800G, but when I install the 2710n in place of the 2800g in my system the incoming telnet doesn't work. Furthermore, there are other problems with the connectivity to and from the special-purpose PC on the LAN when the 2710n is installed in place of the 2800g, namely:
1. The special-purpose PC at 192.168.1.5 can't telnet out through the router, although the PC at 192.168.1.5 can telnet into the router on 192.168.1.1 and other machines on the 192.168.1.x LAN, and they can telnet into the 192.168.1.5 PC without any problems.
2. The PC at 192.168.1.5 can't ping anything on the Internet through the router, although it can successfully ping the router itself and other machines on the 192.168.1.x LAN.
3. The PC at 192.168.1.5 can't resolve any external hostnames or IP addresses.
4. The 2710n router's NAT Sessions listings don't show anything for the PC at 192.168.1.5 even when that PC is trying to communicate with the outside world.
When the 2800g rather than the 2710n is installed, the PC at 192.168.1.5 can do all of the above successfully so it seems to me that something to do with the 2710n is preventing the PC at 192.168.1.5 from reaching the outside world, even though all the other PCs on the LAN side seem to be able to get out OK.
I've searched through all the 2710n's config settings and have tried all sorts of things, including opening all ports to expose the PC at 192.168.1.5 to the wider world but it still refuses to communicate through the router!
The special-purpose PC at 192.168.1.5 is running DOS-based software (yes, I know :o) on an ancient P75 machine; it churns away for months on end without needing rebooting. Sadly, until I can work out how to get this PC communicating through the 2710n I'm going to have to continue to use the 2800g so that the external users can still access the special-purpose PC (and it can access other systems throughout the world). I'd prefer to use the 2710n because if for no other reason than it seems to achieve ADSL sync at a speed about 20% faster than the 2800g (which has the most recent firmware).
Anyone got any ideas why the 2710n isn't letting the telnets, pings, DNS lookups etc from the PC at 192.168.1.5 through to the outside world? Have I missed something in the 2710n's config settings? It's as though the router's firewall is stopping the connectivity between the PC at 192.168.1.5 and the Internet, but I haven't changed any of the firewall settings... :?
TIA
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Martin Davies
