Intermittently ECP access denied on local computer

[Don_Vlogeer]

when trying to access ecp from user local machine intermittently we will get the http error 403, access was denied. however if we refresh the page couple time it will eventually let us through. 

this behavior only observed in local computer, if we try to access ecp from exchange server the issue cannot be reproduced.  

if anyone encounter such issue before and any resolution so far. 

Thank you in advanced. 

[#2]

Hey @Don_Vlogeer we have the same thing on Exchange 2013 (soon to install 2019, so interesting to see if it occurs there as well).

I think it began after entering IP restrictions on the ECP site to prevent external access to that.  The IP address I am accessing the ECP from is permitted but I have to press F5 several times, and the page slowly becomes more accessible.

I was thinking of perhaps removing the IIS IP restrictions and restricting it from the firewall instead.

[#3]

Hey thank for the respond.
I tried removing all the IP address from IIS and immediately could not assess ECP.

However when I add IP address to allow, ECP is working not getting http 403.

not sure from where it is restricting my access.