i have an sophos UTM with L2TP over IPsec VPN and IOS 14.0.1 (IPhone se2020)
so i change the IPsec Policy in "Remote Access -> IPsec -> L2TP-over-IPsec (Policy used for L2TP-over-IPsec)"--> IPsec encryption algorithm: 3DES
--> IPsec authentication algorithm: SHA2 256
Restart the L2TP over IPsec VPN with the switch and
now it works