Asus RT-AC68U: WAN speed is 100mbit only

[ND1]

Hello. Don't know what to try anything else. Here is the story.

Couple days ago I noticed that internet speed became only 100mbit instead of 300mbit, that ISP promised. I made a call and they told me that everything is ok on their side and I have "cable breach".
Well, cable is OK but I've noticed that WAN is 100mbit only in AC68U admin web panel.

What I did:
1. On factory firmware (380.xxx_don't remember exact version) I tried to turn router off, make a factory reset - nothing helped.
2. I've installed 384.19 from Asuswrt-merlin, made factory reset again - same story, just 100mbit.

But if I plug ISP cable just straight to PC - I get full ISP speed 300mbit.

It's AC68U hardware issue? I don't know, maybe it has some 1gbit chip broken and some other, only 100mbit chip left alive?

 

[ColinTaylor]

Replace the Ethernet cable between the modem and the router.

 

[ND1]

Replace the Ethernet cable between the modem and the router.

I don't have any modem. It is just cable to my house from ISP centralised network. And I have full speed without using the router. Something is with the router, not cable.

 

[ColinTaylor]

Try swapping the cable anyway just to eliminate it as a potential cause.

 

[ND1]

It's not possible, because cable is about 20m long and goes to secured ISP switch something in the building. Cable isn't broken.
It can be swapped only by service team with additional cost, but anyway - they will tell me in that scenario, that without router - everything is ok. And it's true...

 

[OzarkEdge]

If you momentarily connect the ISP Ethernet to a router LAN port, does the router status show it connecting at 1 Gbps or 100 Mbps?

OE

 

[ND1]

If you momentarily connect the ISP Ethernet to a router LAN port, does the router status show it connecting at 1 Gbps or 100 Mbps?

OE

It's very strange.
I tried to connect ISP cable to the LAN 1 - it showed up as 1Gbps, then I re-plug it to WAN - it also became 1Gbps, but speed remains as 100 Mbps.

 

[L&LD]

Try a switch between your ISP and your router.

 

[ND1]

Try a switch between your ISP and your router.

Something was changed from ISP side? It was everything ok couple years from AC68U purchase...

 

[OzarkEdge]

Something was changed from ISP side? It was everything ok couple years from AC68U purchase...

Be careful not to assume too much... this could keep you from discovering the problem sooner than later.

Inspect the accessible ISP cable and RJ-45 connector for any damage that might cause intermittent performance. Same for router WAN port.

Do you have another Gigabit router you can use to test with?

OE

 

[ND1]

Do you have another Gigabit router you can use to test with?

Yes, I've just made a test with my old router - everything looks OK

ISP Cable is 300/300, ASUS (with different cables) - 100/100.

 

[OzarkEdge]

Yes, I've just made a test with my old router - everything looks OK

View attachment 26939

ISP Cable is 300/300, ASUS (with different cables) - 100/100.

It was suggested above that you try a switch between the ISP cable and your router... to resolve any recent ISP 'incompatibilities'... a long shot now. Maybe you can disable the routing/DHCP functions in your old router and use its LAN ports/switch.

You could also reset your router, flash it again, reset it again, and try it with minimal settings.

OE

 

[slooptoot]

Hi,

I had the same issue, so I plugged the WAN cable to the port 4, instead of port 1.
Now I'm not limited to 100M anymore.

VS