Hi @Phil Lamerton this one needs to go to PSO

Actually there can be plenty of. It is worthwhile to go through the event log and identify from which service/services the delay is occurred.

Some suspects are,

1. HTM connection - If fetching data from HTM DB is delayed, the ABE cannot offer slots within the timeout.
2. SIM - If appointment request is failed at SIM due to some invalid date (missing Location etc.) then again this timeout will be given. There can be processing delays by SIM ultimately resulting in exceeding the timeout.
3. Broadcast Manager related delays (some improvements have been done in last 6.7 releases and 6.8 around this though)

Hi TatSrikaD, 

Please see the relevant link regarding gateway timeout for some options and let us know the outcome and if it still happening after. 

Kind regards, 

jamie