diff --git a/docs/example.nginx.conf b/docs/example.nginx.conf
index 117eb2cc4..8319c657b 100644
--- a/docs/example.nginx.conf
+++ b/docs/example.nginx.conf
@@ -57,9 +57,12 @@ server {
     add_header Access-Control-Allow-Origin "*";
     # add_header X-Frame-Options "SAMEORIGIN";
 
+    set $coop '';
+    if ($uri ~ ^\/sheet\/.*$) { set $coop 'same-origin'; }
+
     # Enable SharedArrayBuffer in Firefox (for .xlsx export)
     add_header Cross-Origin-Resource-Policy cross-origin;
-    add_header Cross-Origin-Opener-Policy same-origin;
+    add_header Cross-Origin-Opener-Policy $coop;
     add_header Cross-Origin-Embedder-Policy require-corp;
 
     # Insert the path to your CryptPad repository root here
diff --git a/lib/defaults.js b/lib/defaults.js
index 329e16f4c..4110e63d4 100644
--- a/lib/defaults.js
+++ b/lib/defaults.js
@@ -48,9 +48,6 @@ Default.httpHeaders = function () {
         "X-XSS-Protection": "1; mode=block",
         "X-Content-Type-Options": "nosniff",
         "Access-Control-Allow-Origin": "*",
-        "Cross-Origin-Resource-Policy": 'cross-origin',
-        "Cross-Origin-Opener-Policy": 'same-origin',
-        "Cross-Origin-Embedder-Policy": 'require-corp',
     };
 };
 
diff --git a/server.js b/server.js
index 0e0c2d79e..60247f47a 100644
--- a/server.js
+++ b/server.js
@@ -60,6 +60,10 @@ var app = Express();
     }
 }());
 
+var applyHeaderMap = function (res, map) {
+    for (let header in map) { res.setHeader(header, map[header]); }
+};
+
 var setHeaders = (function () {
     // load the default http headers unless the admin has provided their own via the config file
     var headers;
@@ -96,14 +100,21 @@ var setHeaders = (function () {
     }
     if (Object.keys(headers).length) {
         return function (req, res) {
+            // apply a bunch of cross-origin headers for XLSX export in FF and printing elsewhere
+            applyHeaderMap(res, {
+                "Cross-Origin-Resource-Policy": 'cross-origin',
+                "Cross-Origin-Opener-Policy": /^\/sheet\//.test(req.url)? 'same-origin': '',
+                "Cross-Origin-Embedder-Policy": 'require-corp',
+            });
+
+            // targeted CSP, generic policies, maybe custom headers
             const h = [
-                    ///^\/pad\/inner\.html.*/,
                     /^\/common\/onlyoffice\/.*\/index\.html.*/,
                     /^\/(sheet|ooslide|oodoc)\/inner\.html.*/,
                 ].some((regex) => {
                     return regex.test(req.url);
                 }) ? padHeaders : headers;
-            for (let header in h) { res.setHeader(header, h[header]); }
+            applyHeaderMap(res, h);
         };
     }
     return function () {};
@@ -139,6 +150,7 @@ app.use(function (req, res, next) {
 
     setHeaders(req, res);
     if (/[\?\&]ver=[^\/]+$/.test(req.url)) { res.setHeader("Cache-Control", "max-age=31536000"); }
+    else { res.setHeader("Cache-Control", "no-cache"); }
     next();
 });