Some SSL VPN drop everyday at the same hour

Hi. I've a little problem with VPN. We have a USG 110 with latest firmware 4.38(AAPH.0). On WAN1 we have a FTTC (unfortunatly just 60/6 mbps)  router, instead on WAN2 we have an antenna (30/3) with PPP connection. Both WAN are in a trunk and they have not ant problem as I saw. We also have 2 IPSEC VPN on WAN1, 18 SSL-VPN on WAN1 and 2 SSL-VPN on WAN2 (just to try). Emplyees connects to VPN and then to they PCs via RDP. Every day at 10.04 and 16.04 - I don't know if it happens every 6 hours.- some SSL-VPN (6 on 20 today) drop and SSL client must be restarted. It happen on VPN connected on both WAN (we moved 2 VPNs on WAN2 just to try). Today, At 10.04 some VPNs dropped, but not on mine that was the double of another in use (we created different user for each employee). I was also connected on the server waiting the hour with teamviewer but had no issue. I checked the server but I could not find anything strange. But the strange is that it happens always on same hour. Last week it was 2 years early, but always at :04 (we restarted it)

I tried also to send me firewall's log but we did not configure properly the "send mail"  so I just have some screenshot... I'm trying configure it tonight (we are in lockdown so I could not access to the firewall directly) to provide a right log but the button on monitor => log don't send me anything.

Does somebody has any hint?