SMB over VPN (IKEv2) not working under 11.4

we have Problems with a SMB connection over VPN under MacOS 11.4

the computer works fine in the company and the file-server (SMB) is reachable

traceroute to 192.168.0.20 (192.168.0.20), 64 hops max, 52 byte packets

 1  xxxxxxxxxxx.intern (192.168.0.XXX)  36.426 ms  35.926 ms  37.643 ms

 2  192.168.0.20 (192.168.0.20)  37.591 ms  42.375 ms  37.579 ms

now the computer is in home office and we configure a VPN (IKEv2) connection. The vpn connection works fine and the link to our telekom system works fine, but when we try to connect to the file-server over smb it won't work.

traceroute to 192.168.0.20 (192.168.0.20), 64 hops max, 52 byte packets

 1  * * *

 2  * *traceroute: sendto: No route to host

traceroute: wrote 192.168.0.20 52 chars, ret=-1

 *

traceroute: sendto: Host is down

 3 traceroute: wrote 192.168.0.20 52 chars, ret=-1

 *traceroute: sendto: Host is down

traceroute: wrote 192.168.0.20 52 chars, ret=-1

 *traceroute: sendto: Host is down

traceroute: wrote 192.168.0.20 52 chars, ret=-1

 *

please could anybody tell me what's going wrong.

thanks