Symbol server not serving symbols

Hi!

I'm having some problems getting the symbol server plugin to work. It seems as if the symbols are indexed correctly and there is data for symbols in the .teamcity artifact. However, lookup produces a "TC maintenance" page. Not sure why. I have enabled to log output that was recommended in some other thread, but it isn't much of a help really. Relevant log output is pasted below.

Anyone has any clue what could be wrong?

Thank you!

[2017-11-17 14:07:34,715] DEBUG [und Build Indexer (metadata) 1] - Stored symbol file signature e090a85f5d4e4b3f840aa8f95a6b86bf for file name ***.**********or.Common.pdb build id 5002

..
..
..

[2017-11-20 10:25:13,020] DEBUG [) {id=17}; http-nio-81-exec-15] - Symbol file requested. File name: ***.**********or.Common. Guid: e090a85f5d4e4b3f840aa8f95a6b86bf.
[2017-11-20 10:25:13,022] DEBUG [) {id=17}; http-nio-81-exec-15] - Guest access enabled on the server. Trying to check permissions of Guest.
[2017-11-20 10:25:13,022] DEBUG [) {id=17}; http-nio-81-exec-15] - Guest user has enough permissions to process request.

Results in this page if i test URL in the browser: