The rail line between Wolverhampton and Shrewsbury is closed until at least Easter due to a landslip with bus replacements in use.
This affects the through trains from Birmingham to the Cambrian Coast and to North Wales (Chester, Conwy and Holyhead for instance).
To and from North Wales divert on the all train route via Crewe.
For the Cambrian Coast it depends where you are travelling to or from. In many cases the bus replacement may be your best option.