We notice on our provider connection collisions due to the halfduplex settings. I contacted our provider and he is telling me that the duplex settings of a cisco 800 routers can't be changed. Can someone confirm me that this is impossible?
Jorg - it depends on the 800-series router, and the interface in question.
I have an 827, which has an ADSL WAN interface, and a 10 Mbit Ethernet Hub as its inside interface. The hub is 10 Mbit Half Duplex, and can't be changed.
The 831 has four 10/100 ports as its inside interface, which are configured via a virtual "Ethernet 0" interface, which you can set both speed and duplex on. The WAN interface is a 10/100 Ethernet port which you can set the speed and duplex on also.
The 837 is just the same as the 831, but has an ADSL WAN interface.
The 857 has the same interfaces as the 837, but is newer.
I've never used any of the other 800 series. If you can tell me which 800 series model you use, we can tell you definitively.
Hope this helps!