strange local lan issues - can't access local NAS IP

Something recently happened such that I no longer can access my NAS on the local lan. All computers are on a single subnet, and other Mac's and PC's can access the NAS using the NAS's IP address. Until today, my iMac could also access the NAS using the NAS's IP address. Something changed on my iMac today. I have tried both Safari and Chrome browsers (on the iMac), neither can access the NAS IP, both browsers time out. I have cleared the cache in safari along with deleting all cookies, that didn't work. I went into keychain and deleted the self-signed certs for the NAS, that didn't work. I'm at a loss for what to do, this issue is isolated to my iMac, which had no problem in the past. Something changed and I don't know where to look to resolve the matter. Any assistance would be greatly appreciated.