NEED HELP：IPSEC VPN with ODBC Database

We recently started using Fortigate 200E 7.2.4 build 1396 as our external network interface. IPSEC VPN was enabled on WAN1 for company employees to access the internal network. Two key issues arose:

Most users worked fine, but some users' VPNs were not stable and would always disconnect automatically.

In addition, some users with Home Internet could connect to the VPN, but they could not use the ODBC driver configured by Microsoft Access to access our database when connected to the VPN, and would always receive various ODBC errors.But the strange thing is that when they switched to mobile hotspot, it worked fine.

I would like to know if anyone knows what the general cause of this situation is? How can I check these issues and fix them?