Safari cannot open the page because server cannot be found

After I install a surveillance system on my home whit the mobil app call DMSS , my home network is not responding on several webpages and get safari error like, safari cannot open the paga because the server can't be found, and this in only wen on wifi, any body have a similar problem or someone knows a solution that be so much help and I appreciate . Thanks for your time

[Re-Titled by Moderator]