Use wintun in windows disconnected for a while

When I have connected after 20-30 min it is will be disconnect.(openconnect is not display disconnect but The VPN network is actually disconnected)

But use default tap-windows is work fine
OS:Windows 10
OpenConnect version:OpenConnect version v8.10-697-g4aacfd48
Using GnuTLS 3.6.15. Features present: PKCS#11, HOTP software token, TOTP software token, Yubikey OATH, System keys, DTLS, ESP
Supported protocols: anyconnect (default), nc, gp, pulse, f5, fortinet, array

Command: openconnect.exe exserver.com:999 -i wintun

ping the ocserv Intranet ip notice "General error"