Oyster and contactless haven't been the same thing for a while. There is I think the odd exception, but as a general rule actual Oyster only works within the original 9 zones.
The total number of stations outside the zones where oyster is accepted is quite small but you can find one on around half of the mainlines out of London.
Watford Junction (West coast main line/Watford DC)
Radlett (Midland mainline)
Potters Bar (East coast Main line)
Cuffley to Hertford North (Hertford loop)
Broxbourne to Hetrford East (West Anglia main line and it's Hertford Branch)
Shenfield (GEML)
Ockenden and Purfleet to Grays (towards southend).
Merstham to Gatwick airport (Brighton mainline,
only ones south of the river)
Epson (Sutton and Mole valley lines)