IPSEC Strongswan issue.

Actually this should be not a issue. 

It is by design and as far as i can remember, this was the case for years. 

Remote Access * can only use the same PSK. 

You can cheese the system, as PSK is only used in IPsec Phase1. So you can build up the tunnel with PSK1, then you change the PSK to PSK2 and build up the next tunnel. The first tunnel will exists until it gets interrupted for whatever reason.

You should switch to a DDNS instead. Or use the same PSK: 

I've seen discussion actually advise using multiple tunnel using the same psk.
However, there's also issue of having too much backhauling to HQ, the firewall can run into issue of recognizing the tunnels since there're multiple gateways with wildcards.

You even see a popup, if you change the PSK in a Wildcard Tunnel. 

Ok according to what u say, correct me if i'm wrong. 
You suggest that when creating the 1st tunnel , i can establish it with psk1.
After successfully establishing 2nd tunnel with psk2 , i can go back to 1st tunnel and change psk1 to psk2 to prevent the tunnel from disconnecting.

Ok according to what u say, correct me if i'm wrong. 
You suggest that when creating the 1st tunnel , i can establish it with psk1.
After successfully establishing 2nd tunnel with psk2 , i can go back to 1st tunnel and change psk1 to psk2 to prevent the tunnel from disconnecting.

But if you reboot the appliance, all "Invalid PSKs" will not be established. 

IPsec works in two phases. Phase 1 is PSK driven. Phase 2 is key driven. So an IPsec Tunnel can life with a invalid PSK, as the key will be renewal ed between both peers without the PSK.