IPsec connection works until first rekey

[philipb232]

Hi,
I have a little problem with an IPsec Site2Site connection. The connection works until the first rekey after one hour.
I'm not sure if I read the log correctly but it looks like the rekey works but the other side tries to rekey again 25 seconds later, but with the old SPI.
Unfortunately I don't have access or detailed information about the other side but maybe someone here is able to spot the problem.