No internet connection with message: The interface is connected but the internet can't be accessed

[dimitrios.tziouris]

• Which router (which model?) are you using?
GL-MT3000

• Which firmware version is in use?
Firmware 4.6.4
OpenWrt Version OpenWrt 21.02-SNAPSHOT r15812+900-46b6ee7ffc
Kernel Version 5.4.211

• How is your router connected to the Internet?
ISP -> DSL port of Huawei DN8245V-70 router (in bridge mode)-> LAN1 port -> LAN cable -> WAN port of GL-MT3000 (-> LAN port -> second LAN cable -> LAN2 port of DN8245V-70)

Settings of Huawei DN8245V-70 in bridge mode:

Default settings of Huawei DN8245V-70 in routing mode:

Settings of GL-MT3000:

Homescreen of GL-MT3000:

• Which DNS server do you use? (The local one of your ISP? AdGuard Home? Another one?)
From my ISP

• Do you use DHCP or static IP addresses?
DN8245V-70: DHCP disabled & set to a static address of 192.168.8.254.
GL-MT3000: DHCP enabled

ping 9.9.9.9
PING 9.9.9.9 (9.9.9.9): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
...

nslookup gl-inet.com
;; connection timed out; no servers could be reached

[admon]

I would try to remove the VLAN ID (=1) from the modem and set it on the GL only.

[alzhao]

Should you use vlan id 835 on the X3000's setting as well?

[dimitrios.tziouris]

Setting VLAN ID to 835 on the GL gives me following message regardless of the settings on the Huawei (VLAN set to 835 or disabled)

PPPoE Connection Log
Oops! Cannot detect services.
If you are unable to dial for a long time and try many times have still not been successful. Please try the following methods:
1.Check if the Internet cable connection is normal.
2.Connect your PC to the ISP modem and make the PPPoE dialing for testing.
You shall contact your Internet Services Provider for help after both methods failed

[admon]

Try to remove all DSL options from your Huawei. Since the GL is doing PPPoE the Huawei don't need to do anything.

No Login, no VLAN, no password. Just modem only mode.