diff --git a/tfjs-backend-webgl/karma.conf.js b/tfjs-backend-webgl/karma.conf.js
index 573d0ac4c8f..447571c98c8 100644
--- a/tfjs-backend-webgl/karma.conf.js
+++ b/tfjs-backend-webgl/karma.conf.js
@@ -40,6 +40,24 @@ const karmaTypescriptConfig = {
   }
 };
 
+const devConfig = {
+  frameworks: ['jasmine', 'karma-typescript'],
+  files: [
+    {pattern: './node_modules/@babel/polyfill/dist/polyfill.js'},
+    'src/setup_test.ts',
+    {pattern: 'src/**/*.ts'},
+  ],
+  preprocessors: {'**/*.ts': ['karma-typescript']},
+  karmaTypescriptConfig,
+  reporters: ['dots', 'karma-typescript']
+};
+
+const browserstackConfig = {
+  ...devConfig,
+  hostname: 'bs-local.com',
+  singleRun: true
+};
+
 module.exports = function(config) {
   const args = [];
   if (config.testEnv) {
@@ -51,34 +69,34 @@ module.exports = function(config) {
   if (config.flags) {
     args.push('--flags', config.flags);
   }
+
+  let extraConfig = null;
+
+  if (config.browserstack) {
+    extraConfig = browserstackConfig;
+  } else {
+    extraConfig = devConfig;
+  }
+
   let exclude = [];
   if (config.excludeTest != null) {
     exclude.push(config.excludeTest);
   }
 
   config.set({
-    frameworks: ['jasmine', 'karma-typescript'],
-    files: [
-      {pattern: './node_modules/@babel/polyfill/dist/polyfill.js'},
-      'src/setup_test.ts',
-      {pattern: 'src/**/*.ts'},
-    ],
-    preprocessors: {'**/*.ts': ['karma-typescript']},
-    karmaTypescriptConfig,
-    reporters: ['dots', 'karma-typescript'],
+    ...extraConfig,
     exclude,
-    colors: true,
-    autoWatch: false,
     browsers: ['Chrome'],
-    singleRun: true,
-    client: {jasmine: {random: false}, args: args},
     browserStack: {
       username: process.env.BROWSERSTACK_USERNAME,
       accessKey: process.env.BROWSERSTACK_KEY
     },
-    captureTimeout: 120000,
+    captureTimeout: 3e5,
     reportSlowerThan: 500,
-    browserNoActivityTimeout: 240000,
+    browserNoActivityTimeout: 3e5,
+    browserDisconnectTimeout: 3e5,
+    browserDisconnectTolerance: 0,
+    browserSocketTimeout: 1.2e5,
     customLaunchers: {
       // For browserstack configs see:
       // https://www.browserstack.com/automate/node
@@ -127,5 +145,6 @@ module.exports = function(config) {
         os_version: '10'
       },
     },
+    client: {jasmine: {random: false}, args: args}
   })
 }
diff --git a/tfjs-backend-webgl/scripts/test-ci.sh b/tfjs-backend-webgl/scripts/test-ci.sh
index 3e49f783f7a..17bd9025334 100755
--- a/tfjs-backend-webgl/scripts/test-ci.sh
+++ b/tfjs-backend-webgl/scripts/test-ci.sh
@@ -20,8 +20,7 @@ if [ "$NIGHTLY" = true ]
 then
   # Run the first karma separately so it can download the BrowserStack binary
   # without conflicting with others.
-  # TODO(lina128): Add back bs_ios_11 once browserstack issue is resolved.
-  yarn run-browserstack --browsers=bs_safari_mac --testEnv webgl1 --flags '{"WEBGL_CPU_FORWARD": false, "WEBGL_SIZE_UPLOAD_UNIFORM": 0}'
+  yarn run-browserstack --browsers=bs_safari_mac,bs_ios_11 --testEnv webgl1 --flags '{"WEBGL_CPU_FORWARD": false, "WEBGL_SIZE_UPLOAD_UNIFORM": 0}'
 
   # Run the rest of the karma tests in parallel. These runs will reuse the
   # already downloaded binary.
diff --git a/tfjs-core/karma.conf.js b/tfjs-core/karma.conf.js
index e000cc4be90..91d5a6ab78e 100644
--- a/tfjs-core/karma.conf.js
+++ b/tfjs-core/karma.conf.js
@@ -43,12 +43,12 @@ const devConfig = {
   ],
   preprocessors: {'**/*.ts': ['karma-typescript']},
   karmaTypescriptConfig,
-  reporters: ['dots', 'karma-typescript'],
+  reporters: ['dots', 'karma-typescript']
 };
 
 const browserstackConfig = {
   ...devConfig,
-  reporters: ['dots', 'karma-typescript'],
+  hostname: 'bs-local.com',
   singleRun: true
 };
 
@@ -99,11 +99,12 @@ module.exports = function(config) {
       username: process.env.BROWSERSTACK_USERNAME,
       accessKey: process.env.BROWSERSTACK_KEY
     },
-    captureTimeout: 6e5,
+    captureTimeout: 3e5,
     reportSlowerThan: 500,
     browserNoActivityTimeout: 3e5,
     browserDisconnectTimeout: 3e5,
-    browserDisconnectTolerance: 3,
+    browserDisconnectTolerance: 0,
+    browserSocketTimeout: 1.2e5,
     customLaunchers: {
       // For browserstack configs see:
       // https://www.browserstack.com/automate/node
@@ -131,7 +132,7 @@ module.exports = function(config) {
       bs_ios_11: {
         base: 'BrowserStack',
         device: 'iPhone X',
-        os: 'iOS',
+        os: 'ios',
         os_version: '11.0',
         real_mobile: true
       },
diff --git a/tfjs-core/scripts/test-ci.sh b/tfjs-core/scripts/test-ci.sh
index 90cdf65970d..0bd570c3c62 100755
--- a/tfjs-core/scripts/test-ci.sh
+++ b/tfjs-core/scripts/test-ci.sh
@@ -25,8 +25,7 @@ then
   # without conflicting with others.
   yarn run-browserstack --browsers=bs_chrome_mac
 
-  # TODO(lina128): Add back bs_ios_11 once browserstack issue is resolved.
-  yarn run-browserstack --browsers=bs_firefox_mac,bs_safari_mac,bs_android_9 --flags '{"HAS_WEBGL": false}' --testEnv cpu
+  yarn run-browserstack --browsers=bs_firefox_mac,bs_safari_mac,bs_ios_11,bs_android_9 --flags '{"HAS_WEBGL": false}' --testEnv cpu
 
   ### The next section tests TF.js in a webworker using the CPU backend.
   echo "Start webworker test."