The 800 - as already established - supports static routing.
Forwarding should be enabled by default.
I think we can help you out - but the configuration info given is confusing.
Can you label a simple diagram with addresses, gateway etc?
Stick figure simple. xx-----XX-----x or something similar? We should be able to clear up some of the muddle.
static route 192.168.253.1 with 192.168.250.0/24 gateway
seems wrong. but much depends on what was intended.
If you can describe what you would like to have happen for routing (vs the route statement above) I'm sure the community can help.
By the way, is the route being entered into the 800 series?