Can not connect to a local network

[NCMau]

High Sierra 10.13.6. iMac 2010. After the last security upgrade, can not connect to the local network. Is there a problem with the upgrade or is it my system?

 

[Fishrrman]

Is this your home network, or a "network" at work (or somewhere else)?

Are you trying to connect via wifi?
Or... are you using ethernet?

If it's wifi, try ethernet if possible.

 

[NCMau]

I have always been able to share files with a second home iMac by having file sharing activated and set privileges to Read and Write. This problem occurred after the last or the last two security upgrades. Apparently something has to be done differently but I can't find out what.


• I have tried WiFi and Ethernet connections

• When going to Finder > Go > Browse, second computer shows > connect as > insert password > connect > access denied in Registered or Guest mode.

• I get the right IP from the DHCP and I have good internet connection to both computers.

• Router has been reset few times