I don’t think so. It is a pretty standard home environment with a fritzbox. Could it be a problem that I did not assign a hostname to the Teddycloud Server? During the flash, the web-frontend suggested to use the IP.
Only other thing I noticed ist some errors during startup of the server:
INFO |toniesJson.c:0057:tonies_update| Updating tonies.json from GitHub...
INFO |cloud_request.c:0158:web_request| Connecting to HTTP server raw.githubusercontent.com:443...
INFO |cloud_request.c:0208:web_request| trying IP: 185.199.108.133
INFO |cloud_request.c:0036:httpClientTlsInitCallbackBase| Initializing TLS...
cyclone/cyclone_crypto/cipher/aes.c:260:47: runtime error: left shift of 238 by 24 places cannot be represented in type 'int'
cyclone/cyclone_crypto/cipher/aes.c:268:55: runtime error: left shift of 204 by 24 places cannot be represented in type 'int'
cyclone/cyclone_crypto/cipher/aes.c:395:34: runtime error: left shift of 228 by 24 places cannot be represented in type 'int'
INFO |cloud_request.c:0071:httpClientTlsInitCallbackBase| Initializing TLS done
cyclone/cyclone_crypto/cipher/aes.c:385:34: runtime error: left shift of 222 by 24 places cannot be represented in type 'int'
cyclone/cyclone_crypto/cipher/aes.c:390:34: runtime error: left shift of 174 by 24 places cannot be represented in type 'int'
src/cyclone/cyclone_crypto/mpi.c:792:48: runtime error: left shift of 141 by 24 places cannot be represented in type 'int'
cyclone/cyclone_crypto/cipher/aes.c:400:34: runtime error: left shift of 203 by 24 places cannot be represented in type 'int'
INFO |cloud_request.c:0308:web_request| HTTP code: 200
Edit: I will try to continue in Teddycloud Error=537 (ESP32) because there someone encountered error 304 as well.