Avanti West Coast has announced that a number of weekend trains will be affected by the uncertainty in strikes and driver availability.
While some areas will have a reduced service the train company says there will be no 'direct' service from Shrewsbury to London Euston on Sundays from August 14. The situation will be reviewed on September 11.
There will be one train an hour to Birmingham. There passengers should be able to use Transport for Wales trains into the county.
An Avanti West Coast spokesperson said: "From 14 August until further notice, we will be introducing a reduced timetable on our services. This is due to the current industrial relations climate which has resulted in severe staff shortages in some grades through increased sickness levels, as well as unofficial strike action by ASLEF members.
"As a result of the above, including the majority of drivers declaring themselves unavailable for overtime, our customers have faced multiple short-notice cancellations on our network which has had a severe impact on their plans.
"The reduced timetable is being introduced to ensure a reliable service is delivered so our customers can travel with greater certainty. This decision was not taken lightly, and we are sorry for the enormous frustration and inconvenience this will cause.
"We urge the rail unions to engage in meaningful industry reform talks around modernising working practices and developing a railway fit for the 21st century. We remain open for talks at any time."