USG 20 SSL VPN client can't connect via SecuExtender

Hi I'm not very familiar with this product, taking over from somebody else.

Trying to connect to an existing SSL VPN setup, but the public IP address has changed (company moved). I've added new user, tried old users, they all work fine when I try the "SSL VPN" login in the backend.

I've changed the SSL port too, was 4443, made it back to 443. didn't change, the error messages are always the same, it seems the SSL handshake fails.

Here is the log from SecuExtender:

[ 2023/05/26 12:06:38 ][SecuExtender Agent][INFO] [ANNE] try to login xxxxx:443
[ 2023/05/26 12:06:38 ][SecuExtender Agent][INFO] Connect to xxxxxx:443
[ 2023/05/26 12:06:40 ][SecuExtender Agent][INFO] Local address is xxxxxxxx
[ 2023/05/26 12:06:40 ][SecuExtender Agent][DEBUG] Connect success.
[ 2023/05/26 12:06:40 ][SecuExtender Agent][DETAIL] Handshake LoopCounter: 0
[ 2023/05/26 12:06:41 ][SecuExtender Agent][DEBUG] Error 10054 reading data from server
[ 2023/05/26 12:06:41 ][SecuExtender Agent][ERROR] Error 0x80090301 querying connection info: SECPKG_ATTR_STREAM_SIZES (0x6)
[ 2023/05/26 12:06:41 ][SecuExtender Agent][ERROR] SSL Handshake failed. (0x6)
[ 2023/05/26 12:06:41 ][SecuExtender Agent][ERROR] Failed to connect to device(1) (0x6)
[ 2023/05/26 12:06:41 ][SecuExtender Agent][ERROR] user login device failed (0x6)
[ 2023/05/26 12:06:41 ][SecuExtender Agent][DEBUG] SSL Connection is going to be closed
[ 2023/05/26 12:06:41 ][SecuExtender Agent][DETAIL] Connection ends.

Thanks a lot for your help