I can actually see problem similar to issue identified here Cannot find Plex Server after upgrade (last working version 1.13.4.5271) - #12 by audelair and here Plex update 1.13.9.5439- Server unreachable - #69 by sa2000 and a few other threads
Basically when remote access is enabled and if the router takes a while to respond to NAT/uPnP request to get the Public IP Address, the server gets locked out for the duration of this time - transient deadlocks for up to 2 minutes. This is clearly visible at 17:07
Oct 22, 2018 17:04:51.406 [0x7f487bfff700] DEBUG - Request: [192.168.1.13:57235 (Subnet)] GET / (10 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:04:51.411 [0x7f4864d59700] DEBUG - Request: [127.0.0.1:56864 (WAN)] GET / (10 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:05:30.217 [0x7f486d623700] DEBUG - Request: [192.168.1.13:51721 (Subnet)] GET / (10 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:05:32.837 [0x7f4879717700] DEBUG - Request: [127.0.0.1:56880 (WAN)] GET / (11 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:07:16.385 [0x7f486d335700] DEBUG - Request: [192.168.1.13:47850 (Subnet)] GET / (12 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:07:19.016 [0x7f486ad59700] DEBUG - Request: [127.0.0.1:56928 (WAN)] GET / (13 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:07:34.374 [0x7f486dbff700] DEBUG - Request: [192.168.1.13:50195 (Subnet)] GET / (14 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:08:04.923 [0x7f486a77d700] DEBUG - Request: [127.0.0.1:56961 (WAN)] GET / (15 live) TLS GZIP Signed-in Token (aramsuchit@gmail.com)
Oct 22, 2018 17:09:02.369 [0x7f486aa6b700] DEBUG - NAT: UPnP, getPublicIP didn't find usable IGD.
Oct 22, 2018 17:09:02.621 [0x7f486aa6b700] WARN - NAT: PMP, got an error: Not Supported by gateway.
Oct 22, 2018 17:09:02.628 [0x7f487b511700] DEBUG - Completed after connection close: [192.168.1.13:57235] 200 GET / (15 live) TLS GZIP 251221ms 31 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.629 [0x7f487b511700] DEBUG - Completed after connection close: [192.168.1.13:38470] 200 GET / (15 live) TLS GZIP 281717ms 17 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.633 [0x7f487b7ff700] DEBUG - Completed after connection close: [192.168.1.13:51721] 200 GET / (15 live) TLS GZIP 212417ms 31 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.635 [0x7f487b7ff700] DEBUG - Completed: [127.0.0.1:56848] 200 GET / (15 live) TLS GZIP 279250ms 1727 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.638 [0x7f487b511700] DEBUG - Completed: [127.0.0.1:56864] 200 GET / (15 live) TLS GZIP 251226ms 1727 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.642 [0x7f487b511700] DEBUG - Completed after connection close: [192.168.1.13:44661] 200 GET / (15 live) TLS GZIP 281378ms 31 bytes (pipelined: 2)
Oct 22, 2018 17:09:02.652 [0x7f487b511700] DEBUG - Completed after connection close: [192.168.1.13:50195] 200 GET / (15 live) TLS GZIP 88278ms 29 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.652 [0x7f487b7ff700] DEBUG - Completed after connection close: [192.168.1.13:47850] 200 GET / (15 live) TLS GZIP 106267ms 29 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.657 [0x7f487b7ff700] DEBUG - Completed: [127.0.0.1:56928] 200 GET / (15 live) TLS GZIP 103641ms 1727 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.657 [0x7f487b511700] DEBUG - Completed: [127.0.0.1:56880] 200 GET / (15 live) TLS GZIP 209820ms 1727 bytes (pipelined: 1)
Oct 22, 2018 17:09:02.661 [0x7f487b7ff700] DEBUG - Completed: [127.0.0.1:56961] 200 GET / (15 live) TLS GZIP 57738ms 1727 bytes (pipelined: 1)
we have requests from plex client apps taking about 2 minutes to complete and they would have timed out before that and gave server unavailable response
this has already been referred to the development team
You could try and see if disabling uPnP in the router would help. You would need to switch to a port forward and manually specified port. If you have no need for remote access, you could disable it until the problem is fixed
