I recently purchased a 50 metre Ethernet cable to run from the modem downstairs to the bedroom upstairs (along the walls as I’m currently in a renting situation), but I can’t straighten the cord to be able to sit flat along the walls.

I’m currently using wall safe double sided type tape that normally works well, but no matter what I try, the cord just comes off the wall due to it being curled.

Any help would be greatly appreciated?

I have attached pictures below of what the cord looks like!