Hello guys, I'm from Korea and become a fan of Mikrotik recently. I bought a RB750Gr3 and replaced my LG router from ISP because LG router only provided me 450M internet while I have 1G access contract. To my surprise, 750Gr3 is even slower as I find ether1 working on 100MB speed.
Link partner advertising: 10-100 half/full, no 1000M at all. I think my cable is OK since I can achieve 450M before the replacement.

If you use the same ethernet port on cable modem, then check ethernet cable conecting cable modem with hEX (and any gadget that might be in between - are you using PoE to power hEX?) ...

Interesting. The OP is using the same cable that gave him a 1G link with his previous router, so I don't think that's it, unless there is something like a POE injector in between, as you say.

But I don't think so, as I'm having much the same issue with my CCR1036-8G-2S+ and my QNAP 10G switch. The CCR claims the switch isn't advertising 10G and links at 5G, over a known good 20m CAT6 cable.

So no solution here, but I recognize the problem.

How you get the link at home! I have faced this problem before, my operator gave me a ONU Modem with 4 Ethernet ports, I just use it as bridge and connect my Mikrotik router after and found that only one of 4 Ethernet ports was Gigabit Ethernet, 3 others where Fast Ethernet.
Maybe here is the same problem!

If you use the same ethernet port on cable modem, then check ethernet cable conecting cable modem with hEX (and any gadget that might be in between - are you using PoE to power hEX?) ...

I cannot find where is the modem perhaps LG guys locked it somewhere, I'm supplying 24V power to Gr3 from 220V socket.

What media (Copper / ADSL / Optical Fiber ) do your ISP use to give you internet?

What media (Copper / ADSL / Optical Fiber ) do your ISP use to give you internet?

It's Optical Fiber, I'll call ISP tomorrow about this issue.

And for sure you have a media converter from Optical Fiber to Ethernet Cable (Or an ONT device) that ca be like in my case!

How you get the link at home! I have faced this problem before, my operator gave me a ONU Modem with 4 Ethernet ports, I just use it as bridge and connect my Mikrotik router after and found that only one of 4 Ethernet ports was Gigabit Ethernet, 3 others where Fast Ethernet.
Maybe here is the same problem!

Thank you for the hint.

THe 750 was the wrong purchase if looking to maximize 1gig connection. The hapax3 was the device you should have picked up. I dont expect you will see much above 600 on the hex, if that.