yes, a firewall would block updates but that also would prevent all improvements done to the mod
Generally the SP also offers the option not to down load updates everytime.
The reshade issue however is related to these updates.
The launcher update which ran automatically updated the rehade settings. But this only works if you also download the other files aswell. This time both updates have to be done, the automatic launcher update and the mod update. Then reshade should work again.
You dont have to do the SP update everyday but every now and then would be a good idea.