so you were able to get in and change the login info? 

But now you can’t get in? 

Try a different web browser as well as make sure you’re not using any password managers. I’ve seen them overwrite a password before. 

Also they are sensitive to upper case/lower case and spaces. So keep that in mind. 

Worse case, you might have to factory reset back and start over. 

How do I factory reset the device?

while powered on push and hold reset until the lights change. Usually under 30 seconds (15)

My router does not have a reset or any buttons for that matter. Any other suggestions?

Also, I was able to get in and change the network name and passwords from the default but not the login credentials. Also, once there, it only offered me two options; one for standard and one for 5g to change. The other two never presented as an option and can still be accessed from the default credentials. 

what router do you have?

If you can get back in, you don’t need to reset. You just need to figure out how to change the guest network settings or disable them if you prefer

That’s the issue, I can’t get back in to change them.  I never changed the login credentials themselves as it was not presented as an option immediately as the name change option for the network was. 

Make and Model: Arris Surfboard SBG8300

thank you @plemans !😁 that worked 

Glad it worked for you!