There will be no rail services at Hastings for a whole day while engineering work takes place.
Work is taking place in the Hastings area on Sunday (May 12) which will close all lines.
Southeastern services between London Charing Cross and Hastings are set to be affected.
Southern services between London Victoria and Ore, between Brighton and Ore and also between Eastbourne and Ashford International will also be disrupted.
Southeastern said buses will replace trains between Robertsbridge and Hastings throughout the day. However, as a result of limited road access, a minibus service will run between Battle and Crowhurst.
Buses will also replace trains between Eastbourne, Bexhill, Ore and Ashford International.
A Southeastern spokesman said non-folding bicycles are not allowed on rail replacement bus services at any time. Folding bicycles are allowed if fully folded.