Newbe problems connecting to my rockpi 4 with putty

First Thing i dit wen i got My Rock pi 4 was to flash ubuntu server server to my eMMC, after that I put the eMMC on the rock pi 4.then i assemble the rock pi 4 and its housing, connected the ethernet cable, and the power cable.
Next i loged in to my router to see wat ip adress it had but there where no new devices connected.
I have at the moment no hdmi monitor available and was planning to make a headless server box, and connect to it with putty.
Can somebody please help me with connecting to my rockpi 4. Would be highly appreciated.
Greetings bert

It’s best to use a serial cable to see what is going on and what the problem is. Rock Pi has a debug serial console on pins 8 and 10.

Please see this wiki page: https://wiki.radxa.com/Rockpi4/dev/serial-console

Otherwise there is no way of knowing what is going on.

Mostly you would need to enable SSH access in the written image. If you can’t connect HDMI monitor and/or keyboard, you would need to edit the system on eMMC. Best for you will be edit provided ISO file.

After-sum frustration i took mijn rock pi 4 to a friend and Attached it to this tv. it worked immediately and I did an upgrade en een update En installed ufw and open ssh server. Took The Thing Back Home and Attached it to my home Network. And wala it works a charm. What I did right I don’t know but I don’t care ,it works. Tomorrow I’m gonna setup my first web server (nginx and php, mysql)and after that my first mail server. Its gona be one big learning experience.
Thank you all for the suport. foobar im stil gonna try out the debug uart. Just to see what kind of output it gives.
Wish you all the best, greetings bert