After updating FW from 3.9.7.2 to 4.3.1.1 I have problems with the stability of the router:
- it restarts itself. Up Time is for several hours. It was weeks before the update.
- once after such launch, there was no contact (data exchange) with the VPN networks even though the VPNs were connected! Hard restart helped.

I checked the reboot time in the Log Server (another machine) and I have:


10.10.1.250 Jul 22 23:49:57 local0 info Tulce [FILTER][Pass][WAN->LAN/RT/VPN, 24:56:58 ][@S:R=51:1, 31.184.198.71:36881->77.65.XX.XX8:22][TCP][HLen=20, TLen=40, Flag=A, Seq=3266744084, Ack=4053789795, Win=64400]
10.10.1.250 Jul 22 23:49:57 local0 info Tulce [FILTER][Pass][WAN->LAN/RT/VPN, 24:56:58 ][@S:R=51:1, 31.184.198.71:36881->77.65.XX.XX8:22][TCP][HLen=20, TLen=40, Flag=A, Seq=3266744084, Ack=4053789845, Win=64350]
10.10.1.250 Jul 22 23:49:57 local0 info Tulce [FILTER][Pass][WAN->LAN/RT/VPN, 24:56:58 ][@S:R=51:1, 31.184.198.71:36881->77.65.XX.XX8:22][TCP][HLen=20, TLen=40, Flag=A, Seq=3266744084, Ack=4053789846, Win=64350]
10.10.1.250 Jul 22 23:49:57 local0 info Tulce [FILTER][Pass][WAN->LAN/RT/VPN, 24:56:58 ][@S:R=51:1, 31.184.198.71:33559->77.65.XX.X10:22][TCP][HLen=20, TLen=204, Flag=AP, Seq=1104448351, Ack=4180041352, Win=63113]
10.10.1.250 Jan 1 00:00:13 local2 info Tulce Local User (MAC=FC-EC-DA-19-DA-2C): 192.168.1.71 DNS -> 192.168.1.1 inquire 0.ubnt.pool.ntp.org
10.10.1.250 Jan 1 00:00:15 local2 info Tulce Local User (MAC=24-5E-BE-43-3D-BE): 10.10.1.90 DNS -> 8.8.8.8 inquire s3.eu-central-1.wasabisys.com
10.10.1.250 Jan 1 00:00:15 local0 info Tulce [FILTER][Pass][LAN/RT/VPN->WAN, 0:00:21 ][@S:R=51:1, 10.10.1.74:1024->194.146.251.101:123][UDP][HLen=20, TLen=76]
10.10.1.250 Jan 1 00:00:15 local2 info Tulce Local User (MAC=00-15-65-1B-CD-20): 10.10.1.74:1024 -> 194.146.251.101:123 (UDP)
10.10.1.250 Jan 1 00:00:15 local0 info Tulce [FW_Session][Pass][12/150000][@S:R=51:1, 10.10.1.74:1024->194.146.251.101:123]
10.10.1.250 Jan 1 00:00:15 local0 info Tulce [FILTER][Pass][LAN/RT/VPN->WAN, 0:00:21 ][@S:R=51:1, 10.10.1.5:49899->77.65.XX.XXX:2222][TCP][HLen=20, TLen=52, Flag=S, Seq=589409585, Ack=0, Win=8192]

Download LOG:

https://mega.nz/file/nrI1AbQS#B7rMQ1z9SXkltsBiQpN9SIatmiaqKfIYWkJECU69We0

I found the RC version on the Taiwanese website.
I updated. We'll see if it helps.

4.3.2_RC3 r220_3406_a5060ec/v23

It doesnt, it makes it worse!

https://forum.draytek.co.uk/viewtopic.php?t=23586&start=160

Thank you for the reports regarding 4.3.2_RC3 firmware. There are a couple of memory related issues in 4.3.2_RC3 that are fixed in the 4.3.2_RC5a firmware. One is related to SSL VPN and the other Wireguard.

4.3.2 RC5a can be downloaded from:
https://www.draytek.co.uk/download/support/Vigor3910_v4.3.2_RC5a.zip

If 4.3.1.1 is working for you then that's the recommended release version (4.3.1.1 link below) but I wanted to mention 4.3.2RC5a for anyone who'd tried 4.3.2_RC3.
https://www.draytek.co.uk/support/downloads/vigor-3910/send/773-vigor-3910/2593-v3910-4311

Been on it since this morning, nothing to report so far. Memory use has stayed stable and I do have a 24/7 SSL vpn connection going.

Edit: Ive gone back to 4.3.1 as stability problems with the 2.5Gbe connections, my laptop wouldnt connect kept starting and dropping where as before it was fine, memory had also gone from 68% to 74% in less than a day, which may be fine, but I couldnt take the risk.

have you tried setting back to default then reloading your backup configurations?