These are exactly the same symptoms that I had experienced. I took the opportunity to upgrade to a 2927ax model (to match with the ax 960 APs in my house) and I am experiencing similar issues with the 4.3.2 firmware specific for that model. The router doesnt seem to hang and become unresponsive, instead it generally crashes and reboots. You'll make it a full day max before this happens. Most of the time the debug log has nothing, but I did get a crash in the last few days (see below for output). If I turn off wireless, the router is stable.

Are other folks using their router standalone or in a network with other DrayTek switches/APs? My router is connected to a P2100 switch which has a 2 port LAG to a P1085. The P1085 powers four 960 APs. All these devices are managed by the router, so I was wondering if that was an issue. I tried changing my network to use a managment VLAN and better segmentation of IoT devices etc into VLANs, but this has made no difference. I started thinking my issue was environmental, so took a closer look at temperature (using the Draytek thermometer). My router is in a slim cabinet with the P2100 switch and it has the antennas connected using the DrayTek antenna bases. However, after removing it from the cabinet it still crashed with the antennas connected directly sitting on my desk. The only other thing I have enabled is WCF and DrayDDNS, so my setup isn't super complex.

I've reported all this to support but I am getting very little traction. I would be interested to enabling deeper debugging logging if folks are aware of how to enable that. I've been using DrayTek kit for years with zero complaints - I've hit a few bugs, but they can usually be worked around - but the lack of support and deep technical inspection and help from support on this one are very disappointing.

Here's the debug log output:

Type ? for command help
> sys ver dbg

Router Model: Vigor2927ax Version: 4.3.2 English
Profile version: 4.0.0 Status: 1 (0xc49a7828)
Router IP: 10.0.0.1 Netmask: 255.255.255.0
Firmware Build Date/Time: Dec 2 2021 13:17:02
Router Name: DrayTek
Revision: 2399_e5ff078 master_V2927_432
Router serial no: None

---

firmware exception debug info on cpu0

---

EPC=60643d14, Cause=00800008, Status=1100fc03, BadAddr=00000005, RetAddr=60643c4c
exception id=2(TLB Load)
exception occured in TASK Level
task_id=161, SP=0x63749040(4526 bytes free, 312 used bytes)
system tick =1675433
CURRENT_VERSION : 4.3.2_RC6
get from address : 60017000
Dump CPU0 registers:

---

$ 0: 00000000 fffffffe 00000001 0000000f
$ 4: 00000000 00000004 61750000 00000000
$ 8: 00000018 603b5618 6811e7f0 6bdfddf0
$12: ff817a47 00000008 00000000 e80dcba2
$16: 00000005 00000000 6811e740 00000f5b
$20: fffffe00 00000000 00000000 00000100
$24: 00000001 00000000 00000000 6811e740
$28: 62594100 63749040 63720000 60643c4c
List a possible caller functions:

---

func( 0)=6021d294
func( 1)=608813d4
func( 2)=603b1dd0
func( 3)=60646698
func( 4)=606095c4
func( 5)=60609718
func( 6)=6062e804
List backtrace functions:

---

func( 0)=60643d14
func( 1)=60646698
func( 2)=606095c4
func( 3)=60609718
func( 4)=6062e804
func( 5)=60596bfc
func( 6)=60618338
func( 7)=6045e0f8
func( 8)=6049d790
func( 9)=6060a2c8
func(10)=6064694c
func(11)=6022f91c
func(12)=62360000
>

To answer your question about usage, my 2927ac is used on my home office desk and connects to my network via a Zyxel POE switch. The switch powers 2 AP960C's, and I have an AP903 in an outside garage connected wirelessly to the network. The AP's are all in a mesh configuration with the 2927ac as the root.

I have 3 VLANs, two of them tagged, and the system is very stable with the 2927ac on 4.2.4.2, provided that I do not attempt to turn on IPv6. (4.3.2 is unstable as others have found).

I bought a 2927ax in order to have the wifi 6 capability as per the 960C's and, hopefully?, solve the IPv6 issue.

Incredibly however, Draytek have launched the 2927ax without mesh capability, despite all the fuss they make about mesh in their marketing blurb, so at present it is sitting gathering dust. Admin here indicated that firmware 4.4.0 would bring mesh capability, but I'm still waiting. How hard can it be?

Regarding Syslog, the only "extra" I know is to run the Draytek syslog server utility on a PC, but hornbyp appears to have a lot more experience with this and may be able to help further if he reads
this.

BTW, if you don't have the original firmware for the 2927ax you can download it here https://fw.draytek.com.tw/Vigor2927ax/

Re ax, I have just discovered it doesn't support Wireless WAN's either, WAN3 and WAN4 are missing on WAN page. Apparently this is due to chipset on ax model.

I hadn't realised that either

Having nothing better to do I've set up my 2927ax as the main router and connected the 2927ac as an AP/mesh root to control the mesh of the other three mesh nodes.

So far the experience appears to be 1) using 4.3.2 (ax specific version) on the 2927ax doesn't cause frequent reboots as it did on the 2927ac and 2) Having IPv6 switched on doesn't cause very frequent reboots as it did on the 2927ac, however, although I obtain a "Global" IPv6 address from my ISP on WAN 1, and the router itself can ping IPv6 addresses, this doesn't appear to be carried through to the LAN settings - only a local link address appears on the LAN settings page, and no devices on the LAN can access IPv6 sites.

(I would add that several routers and/or firmwares ago (2925/2926/2927? can't remember when) IPv6 did actually work, inasmuch as I could connect to sites, although the Test IPv6 sites always reported that ICMPv6 was being blocked)

EDIT - I appear to have solved the IPv6 on the LAN issue - I needed to tick the "Enable RIPng" protocol on the WAN IPv6 settings page. Naturally that tick box doesn't even exist on the Draytek "how to" page here https://www.draytek.com/support/knowledge-base/5784 :roll:

Well finally after nearly two months, support got to the bottom of my crashing issue, it turns out the issue was caused by a software bug that was causing a VPN overflow. Issue will be resolved in FW 4.40 which is due for release soon, apparently.