@ahmedengu 

Hi,

If neither the Archer AX55 nor the laptop computer can negotiate a 1 Gbps link to the ONT, then I wouldn't suspect the AX55 or the laptop, since that would be a big coincidence. 

500 Mbps is not a standardized link speed for Ethernet. It seems the laptop's Ethernet port also senses a problem, but tries to make the best out of it, while the AX55 most likely doesn't support that non-standard link speed of 500 Mbps.

Do you get the same behavior with all four Ethernet ports of the I-240G-B ONT?

  @woozle thanks for your response!

If neither the Archer AX55 nor the laptop computer can negotiate a 1 Gbps link to the ONT, then I wouldn't suspect the AX55 or the laptop, since that would be a big coincidence. 

Laptop is able to negotiate 1 Gbps link:

Do you get the same behavior with all four Ethernet ports of the I-240G-B ONT?

The rest are inactive, only one working as configured by ISP

  @ahmedengu 

Ok. Sorry, I misunderstood the "500/500" as link speed.

Well, if the laptop can establish a link speed of 1000 Mbps with the ONT and you have already tested with different cables, then there will be no simple solution for the AX55 only negotiating 100 Mbps.

Do you happen to have an unused Gigabit switch (or another router with Gigabit LAN ports) lying around that you could plug between the ONT and the AX55 ?

woozle wrote

  @ahmedengu 

 

Ok. Sorry, I misunderstood the "500/500" as link speed.

 

Well, if the laptop can establish a link speed of 1000 Mbps with the ONT and you have already tested with different cables, then there will be no simple solution for the AX55 only negotiating 100 Mbps.

 

Do you happen to have an unused Gigabit switch (or another router with Gigabit LAN ports) lying around that you could plug between the ONT and the AX55 ?

 

@woozle No worries.

I don't have a switch, so now the choice comes down to buying a switch or returning the AX55 and buying something else that is hopefully compatible.

Do you by any chance know what might be compatible with Alcatel-Lucent I-240G-B? 

  @ahmedengu 

Theoretically every router with Gigabit Ethernet ports should be compatible with the Alcatel-Lucent I-240G-B. Why some aren't is hard to tell.

I can only say that you might want to stay away from the Archer AX53, AX58 and AX72, as these models are based on the same hardware as the AX55 and thus could potentially show the same symptoms.